Dual depth exit pupil expander

ABSTRACT

An optical device includes a waveguide including an in-coupling optical element configured to in-couple light into the waveguide, a light distributing element configured to receive light from the in-coupling optical element and distribute light at a selected wavelength, and an out-coupling optical element configured to receive light from the light distributing element and out-couple light out of the waveguide. The out-coupling optical element includes a first region configured to out-couple light at a first depth plane based on a lens function of the first region and a second region configured to out-couple light at a second depth plane based on a different lens function of the second region.

INCORPORATION BY REFERENCE

This application claims priority under 35 U.S.C. § 113339(e) from U.S.Provisional Application No. 62/439,848, filed Dec. 28, 2016, entitled“DUAL DEPTH EXIT PUPIL EXPANDER,” which is hereby incorporated byreference herein in its entirety and for all purposes. This applicationadditionally incorporates by reference the entirety of each of thefollowing patent applications: U.S. application Ser. No. 14/555,585filed on Nov. 27, 2014; U.S. application Ser. No. 14/690,401 filed onApr. 18, 2015; U.S. application Ser. No. 14/212,961 filed on Mar. 14,2014; U.S. application Ser. No. 14/331,218 filed on Jul. 14, 2014; andU.S. application Ser. No. 15/072,290 filed on Mar. 16, 2016.

BACKGROUND Field

The present disclosure relates to optical devices, including virtualreality and augmented reality imaging and visualization systems.

Description of the Related Art

Modern computing and display technologies have facilitated thedevelopment of systems for so called “virtual reality” or “augmentedreality” experiences, wherein digitally reproduced images or portionsthereof are presented to a user in a manner wherein they seem to be, ormay be perceived as, real. A virtual reality, or “VR”, scenariotypically involves presentation of digital or virtual image informationwithout transparency to other actual real-world visual input; anaugmented reality, or “AR”, scenario typically involves presentation ofdigital or virtual image information as an augmentation to visualizationof the actual world around the user. A mixed reality, or “MR”, scenariois a type of AR scenario and typically involves virtual objects that areintegrated into, and responsive to, the natural world. For example, inan MR scenario, AR image content may be blocked by or otherwise beperceived as interacting with objects in the real world.

Referring to FIG. 1, an augmented reality scene 10 is depicted wherein auser of an AR technology sees a real-world park-like setting 20featuring people, trees, buildings in the background, and a concreteplatform 30. In addition to these items, the user of the AR technologyalso perceives that he “sees” “virtual content” such as a robot statue40 standing upon the real-world platform 30, and a cartoon-like avatarcharacter 50 flying by which seems to be a personification of a bumblebee, even though these elements 40, 50 do not exist in the real world.Because the human visual perception system is complex, it is challengingto produce an AR technology that facilitates a comfortable,natural-feeling, rich presentation of virtual image elements amongstother virtual or real-world imagery elements.

Systems and methods disclosed herein address various challenges relatedto AR and VR technology.

SUMMARY

Details of one or more implementations of the subject matter describedin this specification are set forth in the accompanying drawings and thedescription below. Other features, aspects, and advantages will becomeapparent from the description, the drawings, and the claims. Neitherthis summary nor the following detailed description purports to defineor limit the scope of the inventive subject matter.

EXAMPLES

1. An eyepiece for a head-mounted display comprising:

-   -   a waveguide having a front face, a rear face and a plurality of        edges, said front face and said rear face having lateral        dimensions, said edges having a thickness less than the lateral        dimensions of said front face and said rear face such that said        waveguide can guide light therein from a location closer to one        edge toward a location closer to another edge by total internal        reflection from said front and rear faces;    -   at least one out-coupling optical element configured to receive        light guided within said waveguide by total internal reflection        from said front face and said rear face and to out-couple light        out of said front face of said waveguide; and    -   at least one optical element having optical power such that said        eyepiece outputs a first portion of said light guided within        said waveguide from a first region of said eyepiece as if said        light originated from a first depth with respect to said        waveguide and a second portion of light guided within said        waveguide from a second region of said eyepiece as if said light        originated from a second depth with respect to said waveguide,        said second region being laterally displaced with respect to        said first region.

2. The eyepiece of Example 1, wherein said at least one optical elementhaving optical power is included in said at least one out-couplingelement.

3. The eyepiece of Example 2, wherein said at least one out-couplingoptical element includes a first region configured to out-couple lightguided within said waveguide as if said light originated from a firstdepth with respect to said waveguide and a second region configured toout-couple light guided within said waveguide as if said lightoriginated from a second depth with respect to said waveguide, saidfirst region of said out-coupling optical element corresponding to saidfirst region of said eyepiece and said second region of saidout-coupling optical element corresponding to said second region of saideyepiece.

4. The eyepiece of any of the examples above, wherein the at least oneout-coupling optical element comprises a diffractive or holographicoptical element.

5. The eyepiece of any of the examples above, wherein the at least oneoptical element having optical power comprises a diffractive orholographic optical element.

6. The eyepiece of Example 4 or 5, wherein the diffractive orholographic optical element comprises an analog surface relief grating(ASR), a binary surface relief structure (BSR), or a switchablediffractive optical element.

7. The eyepiece of Example 1, wherein said at least one optical elementhaving optical power is disposed on said at least one out-couplingelement.

8. The eyepiece of any of the examples above, wherein the at least oneoptical element having optical power comprises a refracting surface thathas optical power.

9. The eyepiece of any of the examples above, wherein the at least oneoptical element having optical power comprises a diffractive orholographic optical element.

10. The eyepiece of any of the examples above, further comprising anin-coupling optical element configured to in-couple light into thewaveguide.

11. The eyepiece of Example 10, wherein the in-coupling optical elementcomprises a wavelength selective optical element configured to couplemore light of a first visible wavelength into said waveguide to beguided therein than a second visible wavelength.

12. The eyepiece of Examples 10 or 11, wherein the in-coupling opticalelement comprises a diffractive optical element.

13. The eyepiece of Example 10, wherein the in-coupling optical elementcomprises a refractive lens.

14. The eyepiece of any of the example above, further comprising a lightdistributing element configured to receive light from the in-couplingoptical element and redirect said light toward said at least oneout-coupling optical element.

15. The eyepiece of any of the examples above, further comprising adisplay configured to provide light for injection into said waveguide.

16. The eyepiece of Example 15, wherein the display comprises a fiberscanning display.

17. The eyepiece of any of the examples above, wherein at least one ofthe first region and the second region of the eyepiece has a fixedoptical power.

18. The eyepiece of any of the above examples, further comprising amultiplexing system configured to selectively distribute a first portionof image content through the first region of the eyepiece and a secondportion of the image content through the second region of the eyepiece.

19. The eyepiece of Example 18, wherein the eyepiece is included in ahead mounted display to be worn on the head of a wearer having a fieldof view that includes said eyepiece and objects forward said eyepiece,the first portion of the image content comprising image content to bepresented in the portion of the field of view of the wearer coincidingwith the first region of the eyepiece while the second portion of theimage content comprises image content to be presented in the portion ofthe field of view of the wearer coinciding with the second region of theeyepiece.

20. The eyepiece of Example 19, wherein the image content in the firstportion of the image content is not visible to the wearer in the portionof the field of view of the wearer coinciding with the second region ofthe eyepiece while the image content in the second portion of the imagecontent is not visible to the wearer in the portion of the field of viewof the wearer coinciding with the first region of the eyepiece.

21. The eyepiece of any of Examples 18-20, wherein the first region ofthe eyepiece is forward and central of a wearer's eye while the secondregion of the eyepiece is below the first region, and the image contentpresented through the first region of the eyepiece corresponds to farimage content while the image content presented through the secondregion of the eyepiece corresponds to near image content.

22. The eyepiece of any of Examples 18-21, wherein the multiplexingsystem comprises a polarization modulator and respective first andsecond polarization filters associated with respective first and secondregions of the eyepiece.

23. The eyepiece of any of Examples 18-22, wherein the multiplexingsystem is configured to present a first portion of the image contentcorresponding to first far image content through the first region of theeyepiece while blocking the first portion of the image content fromexiting the second region of the eyepiece.

24. The eyepiece of any of Examples 18-23, where the multiplexing systemis configured to present a second portion of the image contentcorresponding to second near image content through the second region ofthe eyepiece while blocking the second portion of the image content fromexiting the first region of the eyepiece.

25. The eyepiece of any of Examples 22-24, wherein the polarizationmodulator comprises a liquid crystal modulator comprising a liquidcrystal layer disposed between electrodes configured to apply a voltageacross the liquid crystal layer so as to cause linearly polarized lightto rotate polarization angle.

26. The eyepiece of any of Examples 18-21, 23, and 24 wherein, themultiplexer system comprises first and second shutters and the eyepieceis configured to present far image content through the first region ofthe eyepiece while blocking the second region of the eyepiece with thesecond shutter and present near image content through the second regionof the eyepiece at a different time while blocking the first region ofthe eyepiece with the first shutter.

27. The eyepiece of Example 26, wherein the shutters each compriseliquid crystal layers disposed between electrodes arranged to apply avoltage across the liquid crystal layers.

28. The eyepiece of Example 27, wherein the liquid crystal shuttersfurther comprise a polarizer and an analyzer.

29. The eyepiece of Example 28, wherein the polarizer is configured toprovide linearly polarized light that is received by the liquid crystallayer and the liquid crystal layer is configured to rotate thepolarization angle of the linear polarized light depending on thevoltage applied to the liquid crystal layer via the electrodes such thatsaid linear polarization of the light may be made to be parallel orperpendicular to the linear polarization state that is transmitted bythe analyzer.

30. The eyepiece of any of Examples 26-29, wherein when distant imagecontent is to be displayed, the two shutters may be set such that thedistant image content is passed through the first region of the eyepiecewhile the distant image content from the second region of the eyepieceis blocked while when near image content is being displayed, the twoshutters may be set such that the near image content is passed throughthe second region of the eyepiece while the near image content from thefirst region of the eyepiece is blocked.

31. The eyepiece of Example 26, 27, or 30, wherein the eyepiece isincluded in a head mounted display to be worn on the head of a wearerhaving a field of view that includes said eyepiece and objects forwardsaid eyepiece, and the shutters are configured such that light fromobjects forward of the wearer and the head mounted display may passthrough the eyepiece to the wearer's eye regardless of whether theshutters are open or closed.

32. The eyepiece of Example 27, 30, or 31, wherein the eyepiece isincluded in a head mounted display to be worn on the head of a wearerhaving a field of view that includes said eyepiece and objects forwardsaid eyepiece, and the shutters are configured such that light fromobjects forward of the wearer and the head mounted display may passthrough the analyzer regardless of whether the liquid crystal layerrotates linearly polarized light or not.

33. The eyepiece of Example 32, wherein the shutters further comprise ananalyzer but not a polarizer in the optical path between the liquidcrystal layer and objects forward the head mounted display.

34. The eyepiece of any of Examples 31-33, wherein the shutter isconfigured to be selectively opened and closed to allow light from adisplay to pass or be blocked, said display providing image content.

35. The eyepiece of Example 34, further comprising a polarizer disposedto receive light from the display and yield linearly polarized lightthat may be rotated by a liquid crystal layer depending on the voltageapplied to the liquid crystal layer such that the liquid crystal layerand an analyzer that receives light from the liquid crystal layer canoperate as a shutter for the light from the display that may beselectively open and closed to allow light from the display to pass orbe blocked.

36. A head mounted display comprising the eyepiece of any of the claimsabove.

37. The head mounted display of Example 36, further comprising at leastone eye tracking camera configured to track a gaze of a wearer's eye.

38. The head mounted display of Example 36 or 37, further comprising atleast one head pose sensor configured to assist in determining headmovement, head orientation, head position or any combination of thereof.

39. The head mounted display of Example 37 or 38, wherein the eyetracking sensor or the head pose sensor or both are configured to suchthat when a wearer's gaze is directed to the first region of theeyepiece, a display may couple into the eye piece near image content andnot distant image content, and when the wearer's gaze is directed towardthe second region of the eyepiece, the display may couple light into theeyepiece distant image content and not near image content.

40. The head mounted display of any of Examples 36-39, wherein said headmounted display comprises an augmented reality head mounted display.

41. The head mounted display of any of Examples 36-39, wherein said headmounted display comprises a virtual reality head mounted display.

42. An eyepiece for a head-mounted display comprising:

-   -   a first waveguide having a front face, a rear face and a        plurality of edges, said front face and said rear face of said        first waveguide having lateral dimensions, said edges of said        first waveguide having a thickness less than the lateral        dimensions of said front face and said rear face of said first        waveguide such that said first waveguide can guide light therein        from a location closer to one edge toward a location closer to        another edge by total internal reflection from said front and        rear faces of said first waveguide;    -   at least one first in-coupling optical element configured to        in-couple light into said first waveguide, said at least one        first in-coupling optical element comprising a wavelength        selective optical element configured to couple more light of a        first visible wavelength into said first waveguide to be guided        therein than a second visible wavelength;    -   at least one first out-coupling optical element configured to        receive light guided within said first waveguide by total        internal reflection from said front face of said first waveguide        and said rear face of said first waveguide and to out-couple        light out of said front face of said first waveguide;    -   a second waveguide having a front face, a rear face and a        plurality of edges, said front face and said rear face of said        second waveguide having lateral dimensions, said edges of said        second waveguide having a thickness less than the lateral        dimensions of said front face and said rear face of said second        waveguide such that said second waveguide can guide light        therein from a location closer to one edge toward a location        closer to another edge by total internal reflection from said        front and rear faces of said second waveguide;    -   at least one second in-coupling optical element configured to        in-couple light into said second waveguide, said at least one        second in-coupling optical element comprising a wavelength        selective optical element configured to couple more light of        said second visible wavelength into said second waveguide to be        guided therein than the first visible wavelength;    -   at least one second out-coupling optical element configured to        receive light guided with said second waveguide by total        internal reflection from said front face of said second        waveguide and said rear face of said second waveguide and to        out-couple light out of said front face of said second        waveguide; and    -   at least one optical element having optical power such that said        eyepiece outputs a first portion of said light guided within        said first waveguide and a first portion of said light guided        within said second waveguide from a first region of said        eyepiece as if said light originated from a first depth with        respect to said first waveguide and said second waveguide, and        outputs a second portion of said light guided within said first        waveguide and a second portion of said light guided within said        second waveguide from a second region of said eyepiece as if        said light originated from a second depth with respect to said        first waveguide and said second waveguide, said second region        being laterally displaced with respect to said first region.

43. The eyepiece of Example 42, wherein said light of a first visiblewavelength comprises one of red, green, and blue light, and wherein saidlight of a second visible wavelength comprises a different one of red,green, and blue light.

44. The eyepiece of Example 42, wherein said at least one firstout-coupling optical element includes a first region configured toout-couple light guided within said first waveguide as if said lightoriginated from a first depth with respect to said first waveguide and asecond region configured to out-couple light guided within said firstwaveguide as if said light originated from a second depth with respectto said first waveguide, and said at least one second out-couplingoptical element includes a first region configured to out-couple lightguided within said second waveguide as if said light originated from afirst depth with respect to said waveguide and a second regionconfigured to out-couple light guided within said second waveguide as ifsaid light originated from a second depth with respect to said secondwaveguide, said first region of said at least one first out-couplingoptical element and said first region of said at least one secondout-coupling optical element corresponding to said first region of saideyepiece, and said second region of said at least one first out-couplingoptical element and said second region of said at least one secondout-coupling optical element corresponding to said second region of saideyepiece.

45. A head-mounted display comprising:

-   -   a display configured to output light; and    -   an eyepiece comprising:        -   at least one waveguide configured to guide light therein by            total internal reflection;        -   at least one in-coupling optical element configured to            receive light output by said display and in-couple said            light into said waveguide;        -   at least one out-coupling optical element configured to            receive light guided within said waveguide and to out-couple            light out of said waveguide; and        -   at least one optical element having optical power such that            said eyepiece outputs a first portion of said light guided            within said at least one waveguide as if said light            originated from a first depth with respect to said at least            one waveguide, and a second portion of said light guided            within said at least one waveguide as if said light            originated from a second depth with respect to said at least            one waveguide, said second region being laterally displaced            with respect to said first region.

46. The head-mounted display of Example 45, wherein said displaycomprises a fiber scanning display.

47. The head-mounted display of Example 45, wherein said at least oneout-coupling optical element includes a first region configured toout-couple light guided within said at least one waveguide as if saidlight originated from a first depth with respect to said at least onewaveguide and a second region configured to out-couple light guidedwithin said at least one waveguide as if said light originated from asecond depth with respect to said at least one waveguide, said firstregion of said at least one out-coupling optical element correspondingto said first region of said eyepiece and said second region of said atleast one out-coupling optical element corresponding to said secondregion of said eyepiece.

48. A head-mounted display comprising an eyepiece partitioned into afirst section configured to project a first image to an eye of a wearerand a second section configured to project a second image to the eye ofthe wearer, wherein the first section has a first optical power, and thesecond section has a second optical power different from the firstoptical power, such that the second section image is projected as iffrom a different depth plane than the first image.

49. The head-mounted display of Example 48, wherein the first region andthe section region are laterally spaced within the field of view of theeye of the wearer.

50. The head-mounted display of Example 48, wherein the optical power ofat least one of the first section and the second section isreconfigurable.

51. The head-mounted display of Example 48, wherein the head-mounteddisplay comprises a virtual reality display.

52. The head-mounted display of Example 48, wherein the head-mounteddisplay comprises an augmented reality display.

53. The eyepiece of any of Examples 18-22, wherein the multiplexingsystem is configured to present a first portion of the image contentthrough the first region of the eyepiece while blocking the firstportion of the image content from exiting the second region of theeyepiece.

54. The eyepiece of any of Examples 18-22, and 53, where themultiplexing system is configured to present a second portion of theimage content through the second region of the eyepiece while blockingthe second portion of the image content from exiting the first region ofthe eyepiece.

55. An eyepiece for a head mounted display comprising:

-   -   a waveguide having a front face, a rear face and a plurality of        edges, said front face and said rear face having lateral        dimensions, said edges having a thickness less than the lateral        dimensions of said front face and said rear face such that said        waveguide can guide light therein from a location closer to one        edge toward a location closer to another edge by total internal        reflection from said front and rear faces;    -   at least one out-coupling optical element configured to receive        light guided within said waveguide by total internal reflection        from said front face and said rear face and to out-couple light        out of said front face of said waveguide; and    -   at least one optical element having optical power such that said        eyepiece outputs a first portion of said light guided within        said waveguide from a first region of said eyepiece as if said        light originated from a first depth with respect to said        waveguide and a second portion of light guided within said        waveguide from a second region of said eyepiece as if said light        originated from a second depth with respect to said waveguide,        said second region being laterally displaced with respect to        said first region.

56. The eyepiece of Example 55, wherein said at least one opticalelement having optical power is included in or disposed on said at leastone out-coupling element.

57. The eyepiece of Example 56, wherein said at least one out-couplingoptical element includes a first region configured to out-couple lightguided within said waveguide as if said light originated from a firstdepth with respect to said waveguide and a second region configured toout-couple light guided within said waveguide as if said lightoriginated from a second depth with respect to said waveguide, saidfirst region of said at least one out-coupling optical elementcorresponding to said first region of said eyepiece and said secondregion of said at least one out-coupling optical element correspondingto said second region of said eyepiece.

58. The eyepiece of Example 55, wherein at least one of the at least oneout-coupling optical element or the at least one element having opticalpower comprises a diffractive or holographic optical element.

59. The eyepiece of Example 58, wherein the diffractive or holographicoptical element comprises an analog surface relief grating (ASR), abinary surface relief structure (BSR), or a switchable diffractiveoptical element.

60. The eyepiece of Example 55, wherein the at least one optical elementhaving optical power comprises a refracting surface that has opticalpower.

61. The eyepiece of Example 55, further comprising an in-couplingoptical element configured to in-couple light into the waveguide.

62. The eyepiece of Example 55, further comprising a light distributingelement configured to receive light from the in-coupling optical elementand redirect said light toward said at least one out-coupling opticalelement.

63. The eyepiece of Example 55, wherein at least one of the first regionand the second region of the eyepiece has a fixed optical power.

64. The eyepiece of Example 55, further comprising a multiplexing systemconfigured to selectively distribute a first portion of image contentthrough the first region of the eyepiece and a second portion of theimage content through the second region of the eyepiece.

65. The eyepiece of Example 64, wherein the eyepiece is included in ahead mounted display to be worn on the head of a wearer having a fieldof view that includes said eyepiece and objects forward said eyepiece,the first portion of the image content comprising image content to bepresented in the portion of the field of view of the wearer coincidingwith the first region of the eyepiece while the second portion of theimage content comprises image content to be presented in the portion ofthe field of view of the wearer coinciding with the second region of theeyepiece.

66. The eyepiece of Example 65, wherein the image content in the firstportion of the image content is not visible to the wearer in the portionof the field of view of the wearer coinciding with the second region ofthe eyepiece while the image content in the second portion of the imagecontent is not visible to the wearer in the portion of the field of viewof the wearer coinciding with the first region of the eyepiece.

67. The eyepiece of Example 64, wherein the first region of the eyepieceis forward and central of a wearer's eye while the second region of theeyepiece is below the first region, and the image content presentedthrough the first region of the eyepiece corresponds to far imagecontent while the image content presented through the second region ofthe eyepiece corresponds to near image content.

68. The eyepiece of Example 64, wherein the multiplexing systemcomprises a polarization modulator and respective first and secondpolarization filters associated with respective first and second regionsof the eyepiece.

69. The eyepiece of Example 68, wherein the polarization modulatorcomprises a liquid crystal modulator comprising a liquid crystal layerdisposed between electrodes configured to apply a voltage across theliquid crystal layer so as to cause linearly polarized light to rotatepolarization angle.

70. The eyepiece of Example 64, wherein the multiplexing system isconfigured to present a first portion of the image content correspondingto first far image content through the first region of the eyepiecewhile blocking the first portion of the image content from exiting thesecond region of the eyepiece.

71. The eyepiece of Example 64, where the multiplexing system isconfigured to present a second portion of the image contentcorresponding to second near image content through the second region ofthe eyepiece while blocking the second portion of the image content fromexiting the first region of the eyepiece.

72. The eyepiece of Example 64, wherein the multiplexer system comprisesfirst and second shutters and the eyepiece is configured to present farimage content through the first region of the eyepiece while blockingthe second region of the eyepiece with the second shutter and presentnear image content through the second region of the eyepiece at adifferent time while blocking the first region of the eyepiece with thefirst shutter.

73. The eyepiece of Example 72, wherein the shutters each compriseliquid crystal layers disposed between electrodes arranged to apply avoltage across the liquid crystal layers.

74. The eyepiece of Example 73, wherein the liquid crystal shuttersfurther comprise a polarizer and an analyzer.

75. The eyepiece of Example 74, wherein the polarizer is configured toprovide linearly polarized light that is received by the liquid crystallayer and the liquid crystal layer is configured to rotate thepolarization angle of the linear polarized light depending on thevoltage applied to the liquid crystal layer via the electrodes such thatsaid linear polarization of the light may be made to be parallel orperpendicular to the linear polarization state that is transmitted bythe analyzer.

76. The eyepiece of Example 72, wherein when distant image content is tobe displayed, the two shutters may be set such that the distant imagecontent is passed through the first region of the eyepiece while thedistant image content from the second region of the eyepiece is blockedwhile when near image content is being displayed, the two shutters maybe set such that the near image content is passed through the secondregion of the eyepiece while the near image content from the firstregion of the eyepiece is blocked.

77. A head mounted display comprising:

-   -   a frame configured to mount on a wearer;    -   an eyepiece comprising:        -   a waveguide having a front face, a rear face and a plurality            of edges, said front face and said rear face having lateral            dimensions, said edges having a thickness less than the            lateral dimensions of said front face and said rear face            such that said waveguide can guide light therein from a            location closer to one edge toward a location closer to            another edge by total internal reflection from said front            and rear faces;        -   at least one out-coupling optical element configured to            receive light guided within said waveguide by total internal            reflection from said front face and said rear face and to            out-couple light out of said front face of said waveguide;            and        -   at least one optical element having optical power such that            said eyepiece outputs a first portion of said light guided            within said waveguide from a first region of said eyepiece            as if said light originated from a first depth with respect            to said waveguide and a second portion of light guided            within said waveguide from a second region of said eyepiece            as if said light originated from a second depth with respect            to said waveguide, said second region being laterally            displaced with respect to said first region; and    -   a display configured to selectively couple into the eyepiece        light comprising near image content and light comprising distant        image content.

78. The head mounted display of Example 77, further comprising at leastone eye tracking camera configured to track a gaze of the wearer's eye.

79. The head mounted display of Example 78, wherein the eye trackingcamera is configured such that when the wearer's gaze is directed to thefirst region of the eyepiece, the display may couple into the eye piecelight comprising near image content and not distant image content, andwhen the wearer's gaze is directed toward the second region of theeyepiece, the display may couple into the eyepiece light comprisingdistant image content and not near image content.

80. The head mounted display of Example 77, further comprising at leastone head pose sensor configured to assist in determining at least one ofhead movement, head orientation, and head position.

81. The head mounted display of Example 80, wherein the head pose sensoris configured such that the display selectively couples into theeyepiece light comprising near image content and not distant imagecontent, or light comprising distant image content and not near imagecontent, based on at least one of the head movement, head orientation,and head position of the wearer.

82. The head mounted display of Example 77, wherein said head mounteddisplay comprises an augmented reality head mounted display.

83. The head mounted display of Example 77, wherein said head mounteddisplay comprises a virtual reality head mounted display.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a user's view of augmented reality (AR) through an ARdevice.

FIG. 2 illustrates an example of a wearable display system.

FIG. 3 illustrates a conventional display system for simulatingthree-dimensional imagery for a user.

FIG. 4 illustrates aspects of an approach for simulatingthree-dimensional imagery using multiple depth planes.

FIGS. 5A-5C illustrate relationships between radius of curvature andfocal radius.

FIG. 6 illustrates an example of a waveguide stack for outputting imageinformation to a user.

FIG. 7 illustrates an example of exit beams outputted by a waveguide.

FIG. 8 illustrates an example of a stacked waveguide assembly in whicheach depth plane includes images formed using multiple differentcomponent colors.

FIG. 9A illustrates a cross-sectional side view of an example of a setof stacked waveguides that each includes an incoupling optical element.

FIG. 9B illustrates a perspective view of an example of the plurality ofstacked waveguides of FIG. 9A.

FIG. 9C illustrates a top-down plan view of an example of the pluralityof stacked waveguides of FIGS. 9A and 9B.

FIG. 10A schematically illustrates a perspective view of an example of aplurality of stacked waveguides including a dual depth exit pupilexpander.

FIGS. 10B-10E schematically illustrate top-down plan views of example ofa plurality of stacked waveguides including a dual depth exit pupilexpander.

FIG. 11A schematically illustrates a multiplexing system comprising apolarization modulator and respective first and second polarizationfilters associated with respective first and second regions of the exitpupil expander that are configured to present far image content throughthe first region while blocking the second region and present near imagecontent through the second region at a different time while blocking thefirst region by modulating the polarization depending on whether far ornear image content is to be presented.

FIG. 11B schematically illustrates another time division multiplexingsystem comprising first and second shutters associated with first andsecond regions of the exit pupil expander that are configured to presentfar image content through the first region while blocking the secondregion with the second shutter and present near image content throughthe second region at a different time while blocking the first regionwith the first shutter.

DETAILED DESCRIPTION

Reference will now be made to the figures, in which like referencenumerals refer to like parts throughout. It will be appreciated thatembodiments disclosed herein include optical systems, including displaysystems, generally. In some embodiments, the display systems arewearable, which may advantageously provide a more immersive VR or ARexperience. For example, displays containing one or more waveguides(e.g., a stack of waveguides) may be configured to be worn positioned infront of the eyes of a user, or viewer. In some embodiments, two stacksof waveguides, one for each eye of a viewer, may be utilized to providedifferent images to each eye.

Example Display Systems

FIG. 2 illustrates an example of wearable display system 60. The displaysystem 60 includes a display 70, and various mechanical and electronicmodules and systems to support the functioning of that display 70. Thedisplay 70 may be coupled to a frame 80, which is wearable by a displaysystem user or viewer 90 and which is configured to position the display70 in front of the eyes of the user 90. The display 70 may be consideredeyewear in some embodiments. In some embodiments, a speaker 100 iscoupled to the frame 80 and configured to be positioned adjacent the earcanal of the user 90 (in some embodiments, another speaker, not shown,is positioned adjacent the other ear canal of the user to providestereo/shapeable sound control). In some embodiments, the display systemmay also include one or more microphones 110 or other devices to detectsound. In some embodiments, the microphone is configured to allow theuser to provide inputs or commands to the system 60 (e.g., the selectionof voice menu commands, natural language questions, etc.), and/or mayallow audio communication with other persons (e.g., with other users ofsimilar display systems. The microphone may further be configured as aperipheral sensor to collect audio data (e.g., sounds from the userand/or environment). In some embodiments, the display system may alsoinclude a peripheral sensor 120 a, which may be separate from the frame80 and attached to the body of the user 90 (e.g., on the head, torso, anextremity, etc. of the user 90). The peripheral sensor 120 a may beconfigured to acquire data characterizing the physiological state of theuser 90 in some embodiments. For example, the sensor 120 a may be anelectrode.

With continued reference to FIG. 2, the display 70 is operativelycoupled by communications link 130, such as by a wired lead or wirelessconnectivity, to a local data processing module 140 which may be mountedin a variety of configurations, such as fixedly attached to the frame80, fixedly attached to a helmet or hat worn by the user, embedded inheadphones, or otherwise removably attached to the user 90 (e.g., in abackpack-style configuration, in a belt-coupling style configuration).Similarly, the sensor 120 a may be operatively coupled by communicationslink 120 b, e.g., a wired lead or wireless connectivity, to the localprocessor and data module 140. The local processing and data module 140may comprise a hardware processor, as well as digital memory, such asnon-volatile memory (e.g., flash memory or hard disk drives), both ofwhich may be utilized to assist in the processing, caching, and storageof data. The data include data a) captured from sensors (which may be,e.g., operatively coupled to the frame 80 or otherwise attached to theuser 90), such as image capture devices (such as cameras), microphones,inertial measurement units, accelerometers, compasses, GPS units, radiodevices, gyros, and/or other sensors disclosed herein; and/or b)acquired and/or processed using remote processing module 150 and/orremote data repository 160 (including data relating to virtual content),possibly for passage to the display 70 after such processing orretrieval. The local processing and data module 140 may be operativelycoupled by communication links 170, 180, such as via a wired or wirelesscommunication links, to the remote processing module 150 and remote datarepository 160 such that these remote modules 150, 160 are operativelycoupled to each other and available as resources to the local processingand data module 140. In some embodiments, the local processing and datamodule 140 may include one or more of the image capture devices,microphones, inertial measurement units, accelerometers, compasses, GPSunits, radio devices, and/or gyros. In some other embodiments, one ormore of these sensors may be attached to the frame 80, or may bestandalone structures that communicate with the local processing anddata module 140 by wired or wireless communication pathways.

With continued reference to FIG. 2, in some embodiments, the remoteprocessing module 150 may comprise one or more processors configured toanalyze and process data and/or image information. In some embodiments,the remote data repository 160 may comprise a digital data storagefacility, which may be available through the internet or othernetworking configuration in a “cloud” resource configuration. In someembodiments, the remote data repository 160 may include one or moreremote servers, which provide information, e.g., information forgenerating augmented reality content, to the local processing and datamodule 140 and/or the remote processing module 150. In some embodiments,all data is stored and all computations are performed in the localprocessing and data module, allowing fully autonomous use from a remotemodule.

The perception of an image as being “three-dimensional” or “3-D” may beachieved by providing slightly different presentations of the image toeach eye of the viewer. FIG. 3 illustrates a conventional display systemfor simulating three-dimensional imagery for a user. Two distinct images190, 200—one for each eye 210, 220—are outputted to the user. The images190, 200 are spaced from the eyes 210, 220 by a distance 230 along anoptical or z-axis that is parallel to the line of sight of the viewer.The images 190, 200 are flat and the eyes 210, 220 may focus on theimages by assuming a single accommodated state. Such 3-D display systemsrely on the human visual system to combine the images 190, 200 toprovide a perception of depth and/or scale for the combined image.

It will be appreciated, however, that the human visual system is morecomplicated and providing a realistic perception of depth is morechallenging. For example, many viewers of conventional “3-D” displaysystems find such systems to be uncomfortable or may not perceive asense of depth at all. Without being limited by theory, it is believedthat viewers of an object may perceive the object as being“three-dimensional” due to a combination of vergence and accommodation.Vergence movements (i.e., rotation of the eyes so that the pupils movetoward or away from each other to converge the lines of sight of theeyes to fixate upon an object) of the two eyes relative to each otherare closely associated with focusing (or “accommodation”) of the lensesand pupils of the eyes. Under normal conditions, changing the focus ofthe lenses of the eyes, or accommodating the eyes, to change focus fromone object to another object at a different distance will automaticallycause a matching change in vergence to the same distance, under arelationship known as the “accommodation-vergence reflex,” as well aspupil dilation or constriction. Likewise, a change in vergence willtrigger a matching change in accommodation of lens shape and pupil size,under normal conditions. As noted herein, many stereoscopic or “3-D”display systems display a scene using slightly different presentations(and, so, slightly different images) to each eye such that athree-dimensional perspective is perceived by the human visual system.Such systems are uncomfortable for many viewers, however, since they,among other things, simply provide a different presentation of a scene,but with the eyes viewing all the image information at a singleaccommodated state, and work against the “accommodation-vergencereflex.” Display systems that provide a better match betweenaccommodation and vergence may form more realistic and comfortablesimulations of three-dimensional imagery contributing to increasedduration of wear and in turn compliance to diagnostic and therapyprotocols.

FIG. 4 illustrates aspects of an approach for simulatingthree-dimensional imagery using multiple depth planes. With reference toFIG. 4, objects at various distances from eyes 210, 220 on the z-axisare accommodated by the eyes 210, 220 so that those objects are infocus. The eyes 210, 220 assume particular accommodated states to bringinto focus objects at different distances along the z-axis.Consequently, a particular accommodated state may be said to beassociated with a particular one of depth planes 240, with has anassociated focal distance, such that objects or parts of objects in aparticular depth plane are in focus when the eye is in the accommodatedstate for that depth plane. In some embodiments, three-dimensionalimagery may be simulated by providing different presentations of animage for each of the eyes 210, 220, and also by providing differentpresentations of the image corresponding to each of the depth planes.While shown as being separate for clarity of illustration, it will beappreciated that the fields of view of the eyes 210, 220 may overlap,for example, as distance along the z-axis increases. In addition, whileshown as flat for ease of illustration, it will be appreciated that thecontours of a depth plane may be curved in physical space, such that allfeatures in a depth plane are in focus with the eye in a particularaccommodated state.

The distance between an object and the eye 210 or 220 may also changethe amount of divergence of light from that object, as viewed by thateye. FIGS. 5A-5C illustrate relationships between distance and thedivergence of light rays. The distance between the object and the eye210 is represented by, in order of decreasing distance, R1, R2, and R3.As shown in FIGS. 5A-5C, the light rays become more divergent asdistance to the object decreases. As distance increases, the light raysbecome more collimated. Stated another way, it may be said that thelight field produced by a point (the object or a part of the object) hasa spherical wavefront curvature, which is a function of how far away thepoint is from the eye of the user. The curvature increases withdecreasing distance between the object and the eye 210. Consequently, atdifferent depth planes, the degree of divergence of light rays is alsodifferent, with the degree of divergence increasing with decreasingdistance between depth planes and the viewer's eye 210. While only asingle eye 210 is illustrated for clarity of illustration in FIGS. 5A-5Cand other figures herein, it will be appreciated that the discussionsregarding eye 210 may be applied to both eyes 210 and 220 of a viewer.

Without being limited by theory, it is believed that the human eyetypically can interpret a finite number of depth planes to provide depthperception. Consequently, a highly believable simulation of perceiveddepth may be achieved by providing, to the eye, different presentationsof an image corresponding to each of these limited number of depthplanes. The different presentations may be separately focused by theviewer's eyes, thereby helping to provide the user with depth cues basedon the accommodation of the eye required to bring into focus differentimage features for the scene located on different depth plane and/orbased on observing different image features on different depth planesbeing out of focus.

FIG. 6 illustrates an example of a waveguide stack for outputting imageinformation to a user. A display system 250 includes a stack ofwaveguides, or stacked waveguide assembly, 260 that may be utilized toprovide three-dimensional perception to the eye/brain using a pluralityof waveguides 270, 280, 290, 300, 310. In some embodiments, the displaysystem 250 is the system 60 of FIG. 2, with FIG. 6 schematically showingsome parts of that system 60 in greater detail. For example, thewaveguide assembly 260 may be part of the display 70 of FIG. 2. It willbe appreciated that the display system 250 may be considered a lightfield display in some embodiments.

With continued reference to FIG. 6, the waveguide assembly 260 may alsoinclude a plurality of features 320, 330, 340, 350 between thewaveguides. In some embodiments, the features 320, 330, 340, 350 may beone or more lenses. The waveguides 270, 280, 290, 300, 310 and/or theplurality of lenses 320, 330, 340, 350 may be configured to send imageinformation to the eye with various levels of wavefront curvature orlight ray divergence. Each waveguide level may be associated with aparticular depth plane and may be configured to output image informationcorresponding to that depth plane. Image injection devices 360, 370,380, 390, 400 may function as a source of light for the waveguides andmay be utilized to inject image information into the waveguides 270,280, 290, 300, 310, each of which may be configured, as describedherein, to distribute incoming light across each respective waveguide,for output toward the eye 210. Light exits an output surface 410, 420,430, 440, 450 of the image injection devices 360, 370, 380, 390, 400 andis injected into a corresponding input surface 460, 470, 480, 490, 500of the waveguides 270, 280, 290, 300, 310. In some embodiments, the eachof the input surfaces 460, 470, 480, 490, 500 may be an edge of acorresponding waveguide, or may be part of a major surface of thecorresponding waveguide (that is, one of the waveguide surfaces directlyfacing the world 510 or the viewer's eye 210). In some embodiments, asingle beam of light (e.g. a collimated beam) may be injected into eachwaveguide to output an entire field of cloned collimated beams that aredirected toward the eye 210 at particular angles (and amounts ofdivergence) corresponding to the depth plane associated with aparticular waveguide. In some embodiments, a single one of the imageinjection devices 360, 370, 380, 390, 400 may be associated with andinject light into a plurality (e.g., three) of the waveguides 270, 280,290, 300, 310.

In some embodiments, the image injection devices 360, 370, 380, 390, 400are discrete displays that each produce image information for injectioninto a corresponding waveguide 270, 280, 290, 300, 310, respectively. Insome other embodiments, the image injection devices 360, 370, 380, 390,400 are the output ends of a single multiplexed display which may, e.g.,pipe image information via one or more optical conduits (such as fiberoptic cables) to each of the image injection devices 360, 370, 380, 390,400. It will be appreciated that the image information provided by theimage injection devices 360, 370, 380, 390, 400 may include light ofdifferent wavelengths, or colors (e.g., different component colors, asdiscussed herein).

In some embodiments, the light injected into the waveguides 270, 280,290, 300, 310 is provided by a light projector system 520, whichcomprises a light module 530, which may include a light emitter, such asa light emitting diode (LED). The light from the light module 530 may bedirected to and modified by a light modulator 540, e.g., a spatial lightmodulator, via a beam splitter 550. The light modulator 540 may beconfigured to change the perceived intensity of the light injected intothe waveguides 270, 280, 290, 300, 310. Examples of spatial lightmodulators include liquid crystal displays (LCD) including a liquidcrystal on silicon (LCOS) displays.

In some embodiments, the display system 250 may be a scanning fiberdisplay comprising one or more scanning fibers configured to projectlight in various patterns (e.g., raster scan, spiral scan, Lissajouspatterns, etc.) into one or more waveguides 270, 280, 290, 300, 310 andultimately to the eye 210 of the viewer. In some embodiments, theillustrated image injection devices 360, 370, 380, 390, 400 mayschematically represent a single scanning fiber or a bundle of scanningfibers configured to inject light into one or a plurality of thewaveguides 270, 280, 290, 300, 310. In some other embodiments, theillustrated image injection devices 360, 370, 380, 390, 400 mayschematically represent a plurality of scanning fibers or a plurality ofbundles of scanning fibers, each of which are configured to inject lightinto an associated one of the waveguides 270, 280, 290, 300, 310. Itwill be appreciated that one or more optical fibers may be configured totransmit light from the light module 530 to the one or more waveguides270, 280, 290, 300, 310. It will be appreciated that one or moreintervening optical structures may be provided between the scanningfiber, or fibers, and the one or more waveguides 270, 280, 290, 300, 310to, e.g., redirect light exiting the scanning fiber into the one or morewaveguides 270, 280, 290, 300, 310.

A controller 560 controls the operation of one or more of the stackedwaveguide assembly 260, including operation of the image injectiondevices 360, 370, 380, 390, 400, the light source 530, and the lightmodulator 540. In some embodiments, the controller 560 is part of thelocal data processing module 140. The controller 560 includesprogramming (e.g., instructions in a non-transitory medium) thatregulates the timing and provision of image information to thewaveguides 270, 280, 290, 300, 310 according to, e.g., any of thevarious schemes disclosed herein. In some embodiments, the controllermay be a single integral device, or a distributed system connected bywired or wireless communication channels. The controller 560 may be partof the processing modules 140 or 150 (FIG. 2) in some embodiments.

With continued reference to FIG. 6, the waveguides 270, 280, 290, 300,310 may be configured to propagate light within each respectivewaveguide by total internal reflection (TIR). The waveguides 270, 280,290, 300, 310 may each be planar or have another shape (e.g., curved),with major top and bottom surfaces and edges extending between thosemajor top and bottom surfaces. In the illustrated configuration, thewaveguides 270, 280, 290, 300, 310 may each include out-coupling opticalelements 570, 580, 590, 600, 610 that are configured to extract lightout of a waveguide by redirecting the light, propagating within eachrespective waveguide, out of the waveguide to output image informationto the eye 210. Extracted light may also be referred to as out-coupledlight and the out-coupling optical elements light may also be referredto light extracting optical elements. An extracted beam of light may beoutputted by the waveguide at locations at which the light propagatingin the waveguide strikes a light extracting optical element. Theout-coupling optical elements 570, 580, 590, 600, 610 may, for example,be gratings, including diffractive optical features, as discussedfurther herein. While illustrated disposed at the bottom major surfacesof the waveguides 270, 280, 290, 300, 310, for ease of description anddrawing clarity, in some embodiments, the out-coupling optical elements570, 580, 590, 600, 610 may be disposed at the top and/or bottom majorsurfaces, and/or may be disposed directly in the volume of thewaveguides 270, 280, 290, 300, 310, as discussed further herein. In someembodiments, the out-coupling optical elements 570, 580, 590, 600, 610may be formed in a layer of material that is attached to a transparentsubstrate to form the waveguides 270, 280, 290, 300, 310. In some otherembodiments, the waveguides 270, 280, 290, 300, 310 may be a monolithicpiece of material and the out-coupling optical elements 570, 580, 590,600, 610 may be formed on a surface and/or in the interior of that pieceof material.

With continued reference to FIG. 6, as discussed herein, each waveguide270, 280, 290, 300, 310 is configured to output light to form an imagecorresponding to a particular depth plane. For example, the waveguide270 nearest the eye may be configured to deliver collimated light (whichwas injected into such waveguide 270), to the eye 210. The collimatedlight may be representative of the optical infinity focal plane. Thenext waveguide up 280 may be configured to send out collimated lightwhich passes through the first lens 350 (e.g., a negative lens) beforeit can reach the eye 210; such first lens 350 may be configured tocreate a slight convex wavefront curvature so that the eye/braininterprets light coming from that next waveguide up 280 as coming from afirst focal plane closer inward toward the eye 210 from opticalinfinity. Similarly, the third up waveguide 290 passes its output lightthrough both the first 350 and second 340 lenses before reaching the eye210; the combined optical power of the first 350 and second 340 lensesmay be configured to create another incremental amount of wavefrontcurvature so that the eye/brain interprets light coming from the thirdwaveguide 290 as coming from a second focal plane that is even closerinward toward the person from optical infinity than was light from thenext waveguide up 280.

The other waveguide layers 300, 310 and lenses 330, 320 are similarlyconfigured, with the highest waveguide 310 in the stack sending itsoutput through all of the lenses between it and the eye for an aggregatefocal power representative of the closest focal plane to the person. Tocompensate for the stack of lenses 320, 330, 340, 350 whenviewing/interpreting light coming from the world 510 on the other sideof the stacked waveguide assembly 260, a compensating lens layer 620 maybe disposed at the top of the stack to compensate for the aggregatepower of the lens stack 320, 330, 340, 350 below. Such a configurationprovides as many perceived focal planes as there are availablewaveguide/lens pairings. Both the out-coupling optical elements of thewaveguides and the focusing aspects of the lenses may be static (i.e.,not dynamic or electro-active). In some alternative embodiments, eitheror both may be dynamic using electro-active features.

In some embodiments, two or more of the waveguides 270, 280, 290, 300,310 may have the same associated depth plane. For example, multiplewaveguides 270, 280, 290, 300, 310 may be configured to output imagesset to the same depth plane, or multiple subsets of the waveguides 270,280, 290, 300, 310 may be configured to output images set to the sameplurality of depth planes, with one set for each depth plane. This canprovide advantages for forming a tiled image to provide an expandedfield of view at those depth planes.

With continued reference to FIG. 6, the out-coupling optical elements570, 580, 590, 600, 610 may be configured to both redirect light out oftheir respective waveguides and to output this light with theappropriate amount of divergence or collimation for a particular depthplane associated with the waveguide. As a result, waveguides havingdifferent associated depth planes may have different configurations ofout-coupling optical elements 570, 580, 590, 600, 610, which outputlight with a different amount of divergence depending on the associateddepth plane. In some embodiments, the light extracting optical elements570, 580, 590, 600, 610 may be volumetric or surface features, which maybe configured to output light at specific angles. For example, the lightextracting optical elements 570, 580, 590, 600, 610 may be volumeholograms, surface holograms, and/or diffraction gratings. In someembodiments, the features 320, 330, 340, 350 may not be lenses; rather,they may simply be spacers (e.g., cladding layers and/or structures forforming air gaps).

In some embodiments, the out-coupling optical elements 570, 580, 590,600, 610 are diffractive features that form a diffraction pattern, or“diffractive optical element” (also referred to herein as a “DOE”).Preferably, the DOE's have a sufficiently low diffraction efficiency sothat only a portion of the light of the beam is deflected away towardthe eye 210 with each intersection of the DOE, while the rest continuesto move through a waveguide via TIR. The light carrying the imageinformation is thus divided into a number of related exit beams thatexit the waveguide at a multiplicity of locations and the result is afairly uniform pattern of exit emission toward the eye 210 for thisparticular collimated beam bouncing around within a waveguide.

In some embodiments, one or more DOEs may be switchable between “on”states in which they actively diffract, and “off” states in which theydo not significantly diffract. For instance, a switchable DOE maycomprise a layer of polymer dispersed liquid crystal, in whichmicrodroplets comprise a diffraction pattern in a host medium, and therefractive index of the microdroplets may be switched to substantiallymatch the refractive index of the host material (in which case thepattern does not appreciably diffract incident light) or themicrodroplet may be switched to an index that does not match that of thehost medium (in which case the pattern actively diffracts incidentlight).

In some embodiments, a camera assembly 630 (e.g., a digital camera,including visible light and infrared light cameras) may be provided tocapture images of the eye 210 and/or tissue around the eye 210 to, e.g.,detect user inputs and/or to monitor the physiological state of theuser. As used herein, a camera may be any image capture device. In someembodiments, the camera assembly 630 may include an image capture deviceand a light source to project light (e.g., infrared light) to the eye,which may then be reflected by the eye and detected by the image capturedevice. In some embodiments, the camera assembly 630 may be attached tothe frame 80 (FIG. 2) and may be in electrical communication with theprocessing modules 140 and/or 150, which may process image informationfrom the camera assembly 630 to make various determinations regarding,e.g., the physiological state of the user, as discussed herein. It willbe appreciated that information regarding the physiological state ofuser may be used to determine the behavioral or emotional state of theuser. Examples of such information include movements of the user and/orfacial expressions of the user. The behavioral or emotional state of theuser may then be triangulated with collected environmental and/orvirtual content data so as to determine relationships between thebehavioral or emotional state, physiological state, and environmental orvirtual content data. In some embodiments, one camera assembly 630 maybe utilized for each eye, to separately monitor each eye.

With reference now to FIG. 7, an example of exit beams outputted by awaveguide is shown. One waveguide is illustrated, but it will beappreciated that other waveguides in the waveguide assembly 260 (FIG. 6)may function similarly, where the waveguide assembly 260 includesmultiple waveguides. Light 640 is injected into the waveguide 270 at theinput surface 460 of the waveguide 270 and propagates within thewaveguide 270 by TIR. At points where the light 640 impinges on the DOE570, a portion of the light exits the waveguide as exit beams 650. Theexit beams 650 are illustrated as substantially parallel but, asdiscussed herein, they may also be redirected to propagate to the eye210 at an angle (e.g., forming divergent exit beams), depending on thedepth plane associated with the waveguide 270. It will be appreciatedthat substantially parallel exit beams may be indicative of a waveguidewithout-coupling optical elements that out-couple light to form imagesthat appear to be set on a depth plane at a large distance (e.g.,optical infinity) from the eye 210. Other waveguides or other sets ofout-coupling optical elements may output an exit beam pattern that ismore divergent, which would require the eye 210 to accommodate to acloser distance to bring it into focus on the retina and would beinterpreted by the brain as light from a distance closer to the eye 210than optical infinity.

In some embodiments, a full color image may be formed at each depthplane by overlaying images in each of the component colors, e.g., threeor more component colors. FIG. 8 illustrates an example of a stackedwaveguide assembly in which each depth plane includes images formedusing multiple different component colors. The illustrated embodimentshows depth planes 240 a-240 f, although more or fewer depths are alsocontemplated. Each depth plane may have three or more component colorimages associated with it, including: a first image of a first color, G;a second image of a second color, R; and a third image of a third color,B. Different depth planes are indicated in the figure by differentnumbers for diopters (dpt) following the letters G, R, and B. Just asexamples, the numbers following each of these letters indicate diopters(1/m), or inverse distance of the depth plane from a viewer, and eachbox in the figures represents an individual component color image. Insome embodiments, to account for differences in the eye's focusing oflight of different wavelengths, the exact placement of the depth planesfor different component colors may vary. For example, differentcomponent color images for a given depth plane may be placed on depthplanes corresponding to different distances from the user. Such anarrangement may increase visual acuity and user comfort and/or maydecrease chromatic aberrations.

In some embodiments, light of each component color may be outputted by asingle dedicated waveguide and, consequently, each depth plane may havemultiple waveguides associated with it. In such embodiments, each box inthe figures including the letters G, R, or B may be understood torepresent an individual waveguide, and three waveguides may be providedper depth plane where three component color images are provided perdepth plane. While the waveguides associated with each depth plane areshown adjacent to one another in this drawing for ease of description,it will be appreciated that, in a physical device, the waveguides mayall be arranged in a stack with one waveguide per level. In some otherembodiments, multiple component colors may be outputted by the samewaveguide, such that, e.g., only a single waveguide may be provided perdepth plane.

With continued reference to FIG. 8, in some embodiments, G is the colorgreen, R is the color red, and B is the color blue. In some otherembodiments, other colors associated with other wavelengths of light,including magenta and cyan, may be used in addition to or may replaceone or more of red, green, or blue. In some embodiments, features 320,330, 340, and 350 may be active or passive optical filters configured toblock or selectively light from the ambient environment to the viewer'seyes.

It will be appreciated that references to a given color of lightthroughout this disclosure will be understood to encompass light of oneor more wavelengths within a range of wavelengths of light that areperceived by a viewer as being of that given color. For example, redlight may include light of one or more wavelengths in the range of about620-780 nm, green light may include light of one or more wavelengths inthe range of about 492-577 nm, and blue light may include light of oneor more wavelengths in the range of about 435-493 nm.

In some embodiments, the light source 530 (FIG. 6) may be configured toemit light of one or more wavelengths outside the visual perceptionrange of the viewer, for example, infrared and/or ultravioletwavelengths. In addition, the in-coupling, out-coupling, and other lightredirecting structures of the waveguides of the display 250 may beconfigured to direct and emit this light out of the display towards theuser's eye 210, e.g., for imaging and/or user stimulation applications.

With reference now to FIG. 9A, in some embodiments, light impinging on awaveguide may need to be redirected to in-couple that light into thewaveguide. An in-coupling optical element may be used to redirect andin-couple the light into its corresponding waveguide. FIG. 9Aillustrates a cross-sectional side view of an example of a plurality orset 660 of stacked waveguides that each includes an in-coupling opticalelement. The waveguides may each be configured to output light of one ormore different wavelengths, or one or more different ranges ofwavelengths. It will be appreciated that the stack 660 may correspond tothe stack 260 (FIG. 6) and the illustrated waveguides of the stack 660may correspond to part of the plurality of waveguides 270, 280, 290,300, 310, except that light from one or more of the image injectiondevices 360, 370, 380, 390, 400 is injected into the waveguides from aposition that requires light to be redirected for in-coupling.

The illustrated set 660 of stacked waveguides includes waveguides 670,680, and 690. Each waveguide includes an associated in-coupling opticalelement (which may also be referred to as a light input area on thewaveguide), with, e.g., in-coupling optical element 700 disposed on amajor surface (e.g., an upper major surface) of waveguide 670,in-coupling optical element 710 disposed on a major surface (e.g., anupper major surface) of waveguide 680, and in-coupling optical element720 disposed on a major surface (e.g., an upper major surface) ofwaveguide 690. In some embodiments, one or more of the in-couplingoptical elements 700, 710, 720 may be disposed on the bottom majorsurface of the respective waveguide 670, 680, 690 (particularly wherethe one or more in-coupling optical elements are reflective, deflectingoptical elements). As illustrated, the in-coupling optical elements 700,710, 720 may be disposed on the upper major surface of their respectivewaveguide 670, 680, 690 (or the top of the next lower waveguide),particularly where those in-coupling optical elements are transmissive,deflecting optical elements. In some embodiments, the in-couplingoptical elements 700, 710, 720 may be disposed in the body of therespective waveguide 670, 680, 690. In some embodiments, as discussedherein, the in-coupling optical elements 700, 710, 720 are wavelengthselective, such that they selectively redirect one or more wavelengthsof light, while transmitting other wavelengths of light. Whileillustrated on one side or corner of their respective waveguide 670,680, 690, it will be appreciated that the in-coupling optical elements700, 710, 720 may be disposed in other areas of their respectivewaveguide 670, 680, 690 in some embodiments.

As illustrated, the in-coupling optical elements 700, 710, 720 may belaterally offset from one another. In some embodiments, each in-couplingoptical element may be offset such that it receives light without thatlight passing through another in-coupling optical element. For example,each in-coupling optical element 700, 710, 720 may be configured toreceive light from a different image injection device 360, 370, 380,390, and 400 as shown in FIG. 6, and may be separated (e.g., laterallyspaced apart) from other in-coupling optical elements 700, 710, 720 suchthat it substantially does not receive light from the other ones of thein-coupling optical elements 700, 710, 720.

Each waveguide also includes associated light distributing elements,with, e.g., light distributing elements 730 disposed on a major surface(e.g., a top major surface) of waveguide 670, light distributingelements 740 disposed on a major surface (e.g., a top major surface) ofwaveguide 680, and light distributing elements 750 disposed on a majorsurface (e.g., a top major surface) of waveguide 690. In some otherembodiments, the light distributing elements 730, 740, 750, may bedisposed on a bottom major surface of associated waveguides 670, 680,690, respectively. In some other embodiments, the light distributingelements 730, 740, 750, may be disposed on both top and bottom majorsurface of associated waveguides 670, 680, 690, respectively; or thelight distributing elements 730, 740, 750, may be disposed on differentones of the top and bottom major surfaces in different associatedwaveguides 670, 680, 690, respectively.

The waveguides 670, 680, 690 may be spaced apart and separated by, e.g.,gas, liquid, and/or solid layers of material. For example, asillustrated, layer 760 a may separate waveguides 670 and 680; and layer760 b may separate waveguides 680 and 690. In some embodiments, thelayers 760 a and 760 b are formed of low refractive index materials(that is, materials having a lower refractive index than the materialforming the immediately adjacent one of waveguides 670, 680, 690).Preferably, the refractive index of the material forming the layers 760a, 760 b is 0.05 or more, or 0.10 or less than the refractive index ofthe material forming the waveguides 670, 680, 690. Advantageously, thelower refractive index layers 760 a, 760 b may function as claddinglayers that facilitate TIR of light through the waveguides 670, 680, 690(e.g., TIR between the top and bottom major surfaces of each waveguide).In some embodiments, the layers 760 a, 760 b are formed of air. Whilenot illustrated, it will be appreciated that the top and bottom of theillustrated set 660 of waveguides may include immediately neighboringcladding layers.

Preferably, for ease of manufacturing and other considerations, thematerial forming the waveguides 670, 680, 690 are similar or the same,and the material forming the layers 760 a, 760 b are similar or thesame. In some embodiments, the material forming the waveguides 670, 680,690 may be different between one or more waveguides, and/or the materialforming the layers 760 a, 760 b may be different, while still holding tothe various refractive index relationships noted above.

With continued reference to FIG. 9A, light rays 770, 780, 790 areincident on the set 660 of waveguides. It will be appreciated that thelight rays 770, 780, 790 may be injected into the waveguides 670, 680,690 by one or more image injection devices 360, 370, 380, 390, 400 (FIG.6).

In some embodiments, the light rays 770, 780, 790 have differentproperties, e.g., different wavelengths or different ranges ofwavelengths, which may correspond to different colors. Light rays 770,780, 790 may also be laterally displaced to different locationscorresponding to the lateral locations of in-coupling optical elements700, 710, 720. The in-coupling optical elements 700, 710, 720 eachdeflect the incident light such that the light propagates through arespective one of the waveguides 670, 680, 690 by TIR.

For example, in-coupling optical element 700 may be configured todeflect ray 770, which has a first wavelength or range of wavelengths.Similarly, the transmitted ray 780 impinges on and is deflected by thein-coupling optical element 710, which is configured to deflect light ofa second wavelength or range of wavelengths. Likewise, the ray 790 isdeflected by the in-coupling optical element 720, which is configured toselectively deflect light of third wavelength or range of wavelengths.

With continued reference to FIG. 9A, the deflected light rays 770, 780,790 are deflected so that they propagate through a correspondingwaveguide 670, 680, 690; that is, the in-coupling optical elements 700,710, 720 of each waveguide deflects light into that correspondingwaveguide 670, 680, 690 to in-couple light into that correspondingwaveguide. The light rays 770, 780, 790 are deflected at angles thatcause the light to propagate through the respective waveguide 670, 680,690 by TIR, and thus be guided therein. For example, deflection of lightrays 770, 780, 790 may be caused by one or more reflective, diffractive,and/or holographic optical elements, such as a holographic, diffractive,and/or reflective turning feature, reflector, or mirror. Deflection mayin some cases be caused by microstructure such as diffractive featuresin one or more gratings, and/or holographic and/or diffractive opticalelements configured to turn or redirect light, for example, so as to beguided with the light guide. The light rays 770, 780, 790 propagatethrough the respective waveguide 670, 680, 690 by TIR, being guidedtherein until impinging on the waveguide's corresponding lightdistributing elements 730, 740, 750.

With reference now to FIG. 9B, a perspective view of an example of theplurality of stacked waveguides of FIG. 9A is illustrated. As notedabove, the in-coupled light rays 770, 780, 790, are deflected by thein-coupling optical elements 700, 710, 720, respectively, and thenpropagate by TIR and are guided within the waveguides 670, 680, 690,respectively. The guided light rays 770, 780, 790 then impinge on thelight distributing elements 730, 740, 750, respectively. The lightdistributing elements 730, 740, 750 may comprise one or more reflective,diffractive, and/or holographic optical elements, such as a holographic,diffractive, and/or reflective turning feature, reflector, or mirror.Deflection may in some cases be caused by microstructure such asdiffractive features in one or more gratings, and/or holographic and/ordiffractive optical elements configured to turn or redirect light, forexample, so as to be guided with the light guide. The light rays 770,780, 790 propagate through the respective waveguide 670, 680, 690 by TIRbeing guided therein until impinging on the waveguide's correspondinglight distributing elements 730, 740, 750, where they are deflected,however, in a manner so that the light rays 770, 780, 790 are stillguided within the waveguide. The light distributing elements 730, 740,750 deflect the light rays 770, 780, 790 so that they propagate towardsthe out-coupling optical elements 800, 810, 820, respectively.

The out-coupling optical elements 800, 810, 820 are configured to directlight guided within the waveguide, e.g., the light rays 770, 780, 790,out of the waveguide and toward the viewer's eye. The out-couplingoptical elements 800, 810, 820 may be configured therefore to deflectand redirect the light guided within the waveguide, e.g., light rays770, 780, 790, at a more normal angle with respect to the surfaces ofthe waveguide so as to reduce the effects of total internal reflection(TIR) such that light is not guided within the waveguide but insteadexits therefrom. Moreover, these out-coupling optical elements 800, 810,820 may be configured to deflect and redirect this this light, e.g.,light rays 770, 780, 790, toward the viewer's eye. Accordingly, theout-coupling optical elements 800, 810, 820 may comprise one or morereflective, diffractive, and/or holographic optical elements, such as aholographic, diffractive, and/or reflective turning feature, reflector,or mirror. Deflection may in some cases be caused by microstructure suchas diffractive features in one or more gratings, and/or holographicand/or diffractive optical elements configured to turn or redirectlight, for example, so as to be guided with the light guide. The opticalelements 800, 810, 820 may be configured to reflect, deflect, and/ordiffract the light rays 770, 780, 790 so that they propagate out of thewaveguide toward the users eye.

In some embodiments, the light distributing elements 730, 740, 750 areorthogonal pupil expanders (OPE's). In some embodiments, the OPE's bothdeflect or distribute light to the out-coupling optical elements 800,810, 820 and also replicate the beam or beams to form a larger number ofbeams which propagate to the out-coupling optical elements. As a beamtravels along the OPE's, a portion of the beam may be split from thebeam and travel in a direction orthogonal to the beam, in the directionof out-coupling optical elements 800, 810, 820. Orthogonal splitting ofthe beam in the OPE's may occur repeatedly along the path of the beamthrough the OPE's. For example, OPE's may include a grating having anincreasing reflectance along the beam path such that a series ofsubstantially uniform beamlets are produced from a single beam. In someembodiments, the out-coupling optical elements 800, 810, 820 are exitpupils (EP's) or exit pupil expanders (EPE's) that direct light in aviewer's eye 210 (FIG. 7). The OPE's may be configured to increase thedimensions of the eye box, for example, along the x direction, and theEPE's may be to increase the eye box in an axis crossing, for example,orthogonal to, the axis of the OPE's, e.g., along the y direction.

Accordingly, with reference to FIGS. 9A and 9B, in some embodiments, theset 660 of waveguides includes waveguides 670, 680, 690; in-couplingoptical elements 700, 710, 720; light distributing elements (e.g.,OPE's) 730, 740, 750; and out-coupling optical elements (e.g., EPE's)800, 810, 820 for each component color. The waveguides 670, 680, 690 maybe stacked with an air gap and/or cladding layer between each one. Thein-coupling optical elements 700, 710, 720 redirect or deflect incidentlight (with different in-coupling optical elements receiving light ofdifferent wavelengths) into its respective waveguide. The light thenpropagates at an angle which will result in TIR within the respectivewaveguide 670, 680, 690, and the light is guided therein. In the exampleshown, light ray 770 (e.g., blue light) is deflected by the firstin-coupling optical element 700, and then continues to propagate withinthe waveguide being guided therein, interacting with the lightdistributing element (e.g., OPE's) 730 where it is replicated into aplurality of rays propagating to the out-coupling optical element (e.g.,EPE's) 800, in a manner described earlier. The light rays 780 and 790(e.g., green and red light, respectively) will pass through thewaveguide 670, with light ray 780 impinging on and being deflected byin-coupling optical element 710. The light ray 780 then bounces down thewaveguide 680 via TIR, proceeding on to its light distributing element(e.g., OPE's) 740 where it is replicated into a plurality of rayspropagating to the out-coupling optical element (e.g., EPE's) 810.Finally, light ray 790 (e.g., red light) passes through the waveguide690 to impinge on the light in-coupling optical elements 720 of thewaveguide 690. The light in-coupling optical elements 720 deflect thelight ray 790 such that the light ray propagates to light distributingelement (e.g., OPE's) 750 by TIR, where it is replicated into aplurality of rays propagating to to the out-coupling optical element(e.g., EPE's) 820 by TIR. The out-coupling optical element 820 thenfinally further replicates and out-couples the light rays 790 to theviewer, who also receives the out-coupled light from the otherwaveguides 670, 680.

FIG. 9C illustrates a top-down plan view (or front view) of an exampleof the plurality of stacked waveguides of FIGS. 9A and 9B. Asillustrated, the waveguides 670, 680, 690, along with each waveguide'sassociated light distributing element 730, 740, 750 and associatedout-coupling optical element 800, 810, 820, may be vertically aligned(e.g., along the x and y directions). However, as discussed herein, thein-coupling optical elements 700, 710, 720 are not vertically aligned;rather, the in-coupling optical elements are preferably non-overlapping(e.g., laterally spaced apart along the x direction as seen in thetop-down view of front view in this example). Shifting in otherdirections, such as the y direction, can also be employed. Thisnon-overlapping spatial arrangement facilitates the injection of lightfrom different resources such as different light sources and/or displaysinto different waveguides on a one-to-one basis, thereby allowing aspecific light source to be uniquely coupled to a specific waveguide. Insome embodiments, arrangements including non-overlappinglaterally-separated in-coupling optical elements may be referred to as ashifted pupil system, and the in-coupling optical elements within thesearrangements may correspond to sub-pupils.

In addition to coupling light out of the waveguides, the out-couplingoptical elements 800, 810, 820 may cause the light to be collimated orto diverge as if the light originated from an object at a far distanceor a closer distance, depth, or depth plane. Collimated light, forexample, is consistent with light from an object that is far from theview. Increasing diverging light is consistent with light from an objectthat is closer, for example, 5-10 feet or 1-3 feet, in front of theviewer. The natural lens of the eye will accommodate when viewing anobject closer to the eye and the brain may sense this accommodation,which also then serves as a depth cue. Likewise, by causing the light tobe diverging by a certain amount, the eye will accommodate and perceivethe object to be at closer distance. Accordingly, the out-couplingoptical elements 800, 810, 820 can be configured to cause the light tobe collimated or to diverge as if the light emanated from a far or closedistance, depth, or depth plane. To do so, the out-coupling opticalelements 800, 810, 820 may include optical power. For example, theout-coupling optical elements 800, 810, 820, may include holographic,diffractive, and/or reflective optical elements that in addition todeflecting or re-directing the light out of the waveguides, theseholographic, diffractive, and/or reflective optical elements may furtherinclude optical power to cause the light to be collimated or diverging.The out-coupling optical elements 800, 810, 820 may in the alternativeor in addition include refracting surfaces that include optical powerthat cause the light to be collimated or diverging. The out-couplingoptical elements 800, 810, 820 may therefore comprise, for example, inaddition to diffractive or holographic turning features, a refractivesurface the provides optical power. Such refractive surface may also beincluded in addition to the out-coupling optical elements 800, 810, 820,for example, on top of the out-coupling optical elements 800, 810, 820.In certain embodiments, for example, optical elements, for example,diffractive optical element, holographic optical elements, refractivelens surfaces, or other structures may be disposed with respect to theout-coupling optical elements 800, 810, 820 to provide the optical powercause the collimation or divergence of the light. A layer with opticalpower such as a layer with a refractive surface or a layer withdiffractive and/or holographic features may for example be disposed withrespect to the out-coupling optical elements 800, 810, 820 toadditionally provide optical power. A combination of contributions fromboth the out-coupling optical elements 800, 810, 820 having opticalpower and an additional layer with optical power such as a layer with arefractive surface or a layer with diffractive and/or holographicfeatures is also possible.

Referring now to FIGS. 10A-10E, the out-coupling optical elements 800,810, 820 depicted in FIGS. 9B and 9C may include a plurality ofsub-regions configured to project light as if the light is emanatingfrom different depths or depth planes. For example, the stackedwaveguide assembly 660 may include EPE's 800′, 810′, 820′ havingsub-regions 805, 815, 825, each configured to out-couple the in-coupledlight rays 770, 780, 790 in a sub-region of an EPE 800′, 810′, 820′, aswell as to cause the light to be diverging or collimated as if the lightemanated from a depth different from the depth of the remainder of theEPE 800′, 810′, 820′. As shown in the top-down plan views of FIGS.10B-10E, the sub-regions 805, 815, 825 may be vertically aligned suchthat they occupy the same lateral region when viewed from the top down,e.g., the same region as projected on the x-y coordinate plane asdepicted in FIG. 10A.

Out-coupling of light from the waveguides as if emanating from differentdepths may be accomplished by providing sub-regions 805, 815, 825 withan optical power different from the optical power (if any) of theremainder of the EPE 800′, 810′, 820′. For example, the sub-regions orzones 805, 815, 825 may have a higher or lower optical power so as tofocus the virtual image at a different position within the eyebox, forexample, as if the virtual images in the two regions are projected fromdifferent depths. For instance, the sub-regions 805, 815, 825 mayinclude negative optical power that causes the light to diverge as ifthe light is emanating from a location a couple of feet in front of theviewer, while the remainder of the EPE 800′, 810′, 820′ has no opticalpower or less negative optical power that causes the light to becollimated as if the light originated from a very distant object. Theoptical power of the sub-region 805, 815, 825 may be selected based onthe desired depth of the sub-region 805, 815, 825 relative to theremainder of the EPE, e.g., region or zone 800′, 810′, 820′. In someembodiments, more than two regions of different optical power may beprovided for out-coupling of light 770, 780, 790. As described above,the optical power of each region may be determined by the structure ofthe out-coupling elements or other elements of the system.

Regions may have various shapes or locations within an EPE. For example,sub-region 805, 815, 825 may be located along a top, side (e.g. left orright), or bottom edge of the EPE, and/or may be surrounded within theregion 800′, 810′, 820′.

Region 800′, 810′, 820′ and sub-regions 805, 815,825 may be square,rectangular, trapezoidal, elliptical, etc., as viewed in an x-y plane orother shapes. For example, the implementation depicted in FIG. 10Cincludes a sub-region similar to the sub-region of FIG. 10B, butconfigured to include the extent of the left side of the EPE disposed tothe left of the partition line. The implementation depicted in FIG. 10Dincludes a sub-region located near the top of the EPE, and surroundedwithin the region 800′, 810′, 820′. The implementation depicted in FIG.10E includes an elliptical sub-region located near the right side of theEPE and similarly surrounded within the region 800′, 810′, 820′. Any ofthe shapes, locations, or other qualities of the sub-regions describedand depicted with reference to FIGS. 10B-10E may be combined in variousimplementations. For example, sub-regions 805, 815, 825 may be includedon both the left and right of the EPE, or left and bottom, right andbottom, left and top, or right and top of the EPE. The differentsub-regions 805, 815, 825 may have different sizes and/or shapes whenmultiple sub-regions 805, 815, 825 are included. It may be preferable insome embodiments to locate the sub-region 805, 815, 825 near theperiphery of the EPE, e.g., along an edge or nearer to the peripherythan to the center of the EPE, so as to avoid interfering with primarycontent displayed in region 800′, 810′, 820′. The size of the sub-region805, 815, 825 may be any suitable size for displaying content, such asbetween 5%-10%, 10%-15%, 15%-20%, or 20%-25%, of the entire lateralextent of the EPE (e.g., the horizontal and vertical or x-y lateralextent of the EPE area) or more or less, or any combination of theseranges. Moreover, the transition between the optical power of region800′, 810′, 820′ and the optical power of region 805, 815, 825 may beabrupt or discrete at a border between the optical power regions, or maybe a smooth or gradual transition.

As described above, the out-coupling optical elements 800, 810, 820 maycomprise one or more reflective, diffractive, and/or holographic opticalelements, such as a holographic, diffractive, and/or reflective turningfeature, reflector, or mirror configured to turn or redirect light, forexample, so as to be guided with the light guide. Deflection may in somecases be caused by microstructure such as diffractive features in one ormore gratings, and/or holographic and/or diffractive optical elements.The optical elements 800, 810, 820 may be configured to reflect,deflect, and/or diffract the light rays 770, 780, 790 so that theypropagate out of the waveguide toward the users eye. In addition, theout-coupling optical elements 800, 810, 820, can include optical powerto cause the light to be collimated or to diverge as if the lightemanated from a far or close distance, depth, or depth plane. Forexample, the out-coupling optical elements 800, 810, 820, may includeholographic, diffractive, and/or reflective optical elements that inaddition to deflecting or re-directing the light out of the waveguides,these holographic, diffractive, and/or reflective optical elements mayfurther include optical power to cause the light to be collimated ordiverging. The out-coupling optical elements 800, 810, 820 may alsocomprises a refractive surface that refracts or bends the light toprovide a lensing effect. As described above, different optical powercan be provided to different sections of the out-coupling opticalelements 800, 810, 820. Also as described above the transition betweenthe optical power of region 800′, 810′, 820′ and the optical power ofregion 805, 815, 825 may be abrupt or discrete at a border between theoptical power regions, or may be a smooth or gradual transition. Inexamples where a refractive surface provided optical power, the tworegions or zones of different optical powers may be formed from andcomprise a freeform surface.

Also as described above, in certain embodiments, optical elements, forexample, diffractive optical element, holographic optical elements,refractive lens surfaces, or other structures may be disposed withrespect to the out-coupling optical elements 800, 810, 820 to providethe optical power cause the collimation or divergence of the light. Alayer with optical power such as a layer with a refractive surface or alayer with diffractive and/or holographic features may for example bedisposed with respect to (e.g., on top of) the out-coupling opticalelements 800, 810, 820 to additionally provide optical power. Acombination of contributions from both the out-coupling optical elements800, 810, 820 having optical power and an additional layer with opticalpower such as a layer with a refractive surface or a layer withdiffractive and/or holographic features is also possible. As describedabove, different optical power can be provided to different sections ofthe out-coupling optical elements 800, 810, 820. Also as described abovethe transition between the optical power of region 800′, 810′, 820′ andthe optical power of region 805, 815, 825 may be abrupt or discrete at aborder between the optical power regions, or may be a smooth or gradualtransition. Accordingly, in examples where a refractive surface providesoptical power, the two regions or zones of different optical powers maybe formed from and comprise a freeform surface.

A multiple-depth EPE including regions 805, 815, 825 configured toproject light as if emanating from a depth or depth plane other than thedepth or depth plane associated with of another portion of out-couplingelements 800′, 810′, 820′ may provide several advantages. In someembodiments, the multiple-depth EPE may be provided within a headmounted display to facilitate the simultaneous viewing of a plurality ofdifferent content types (e.g., distant objects versus text) by a wearer.The multiple-depth EPE may provide a more realistic presentation ofcontent at multiple depth planes, and may avoid increasing computerhardware and/or software processing and/or processing requirements,including additional electrical power usage, to generate content atdifferent depths or depth planes. More specifically, projecting imagesappearing at different depths or depth planes in different regions ofthe display using multiple stacked sets of waveguides, one set for eachdepth or depth plane, where each waveguide provides a full frame, maypotentially involve significant additional computation and/orprocessing, which may be a burden on processing resources and frame rateof the display. Thus, the multiple-depth EPE wherein multiple depths ordepth planes are provided for a single waveguide and a single fullframe, can provide content appearing at a plurality of depth planes withreduced impact on processing resources or frame rate in comparison to asystem that provides multiple depths or depth planes using differentwaveguides presenting full frames.

In one example, sub-regions 805, 815, 825 of the EPE's 800′, 810′, 820′can have a lens function that projects light that appears to be comingfrom a focal plane closer inward to the eye than the light projectedfrom the remainder of the EPE's 800′, 810′, 820′. The nearer focal planeof sub-regions 805, 815, 825 can be used to project detailed and/orreadable content. For example, a user may watch virtual content, such asa movie or other visual content, while simultaneously checking e-mail orviewing other detailed content in sub-region 805, 815, 825. Furtherimplementations can include presenting text, captions, a “ticker”display or icons in one sub-region at the bottom or side of the eyepiececontaining readable content such as news, sports information, financialinformation, icons for providing user selection or the like. In oneexample, an augmented reality system may use various recognitionsoftware functions to identify people and/or things within a wearer'sfield of view such that these items may be tagged, flagged, or otherwiseidentified. Augmented content, such as an arrow, highlighted region, orother visual content displayed through the EPE's 800′, 810′, 820′ maydirect the user's attention to a person or item of interest, whiledetailed content, such as words, images, symbols, or other informationassociated with the person or item may be displayed at a closer depthplane in a sub-region 805, 815, 825.

For various types of near and distant content as described above, it maybe desirable to selectively project only the near content through thesub-region 805, 815, 825, while projecting only the distant contentthrough the remainder of the EPE's 800′, 810′, 820′. For example, insome situations the sub-region 805, 815, 825 may be on the lower portionof the EPE's 800′, 810′, 820′ in a location where a viewer would gazedownward to view. This downward gaze is also commonly used to read or toview close-up objects. Accordingly, the sub-region 805, 815, 825, may beconfigured to present near image content while the remainder of theEPE's 800′, 810′, 820′ may be configured to present far image content.Various approaches may be utilized to separate far and near imagecontent into the two regions of each EPE 800′, 810′, 820′, the upper andlower sub-regions.

In one example, as depicted in FIG. 11A, the head mounted displayfurther comprises a multiplexing system 901 configured to distribute afirst portion of image content such as a first portion of a frame (e.g.,video frame) through a first region of the exit pupil expander 800′,810′, 820′ and a second portion of image content such as a secondportion of a frame through a second region of the exit pupil expander800′, 810′, 820′. The first portion of the image content may includeimage content to be presented in the portion of the field of view of thewearer coinciding with the first region of the exit pupil expander 800′,810′, 820′ while the second portion of the image content may includeimage content to be presented in the portion of the field of view of thewearer coinciding with the second region 805, 815, 825 of the exit pupilexpander 800′, 810′, 820′. Additionally, the image content presentedthrough the first portion may be projected as if located at a firstdepth, and the image content presented through the second portion may beprojected as if located at a second depth that is different from thefirst. Accordingly, the second region may have different optical powerthan the first region. This different optical power may cause the lightfrom the second region to diverge in a manner that is different from thepropagation of the light from the first region. In one example, thefirst region is forward and central while the second region 805, 815,825 is below the first region and the image content presented throughthe first region corresponds to far image content while the imagecontent presented through the second region corresponds to near imagecontent.

In the example shown in FIG. 11A, the multiplexing system 901 comprisesa polarization modulator (as well as control electronics configured todrive/control the polarization modulation and establish the appropriatetiming of the modulation) and respective first and second polarizationfilters associated with respective first and second regions of the exitpupil expander 800′, 810′, 820′ that are configured to present a firstportion of the image content corresponding to first (e.g., far) imagecontent through the first region while blocking the first portion of theimage content from exiting the second region 805, 815, 825. Similarly,the multiplexing system 901 is configured to present a second portion ofthe image content corresponding to second (e.g., near) image contentthrough the second region 805, 815, 825 while blocking the secondportion of the image content from exiting the first region. In thisexample, this multiplexing is accomplished by modulating thepolarization using, for example, the control electronics depending onwhether the first portion of the image content/first image content(e.g., the far image content) or second portion of the imagecontent/second image content (e.g., the near image content) is to bepresented. In particular, sub-regions 805, 815, 825 include a polarizingfilter 920 (often referred to herein as the second polarizer) configuredto selectively pass light having a second polarization, while theremainder of the EPE's 800′, 810′, 820′ may include a polarizing filter915 (often referred to herein as the first polarizer) configured toselectively pass light having a first polarization orthogonal orperpendicular to the second polarization passed by the second polarizingfilter 920 of the sub-regions 805, 815, 825. Polarizing filters 915, 920may be included in or integrated with the out-coupling element of eachwaveguide in the waveguide stack, or may be a single filter located atthe exterior eye-facing surface of the EPE's 800′, 810′, 820′. Thepolarization filters 915, 920, for example, may comprise polarizationgratings that couple light of a particular polarization out of thewaveguide. Image content for both the sub-regions 805, 815, 825 and theremainder of the EPE's 800′, 810′, 820′ may be injected into thewaveguide stack 660 in a polarization-multiplexed beam. A near componentof the polarization-multiplexed beam can include the image content to bedisplayed in the sub-region 805, 815, 825, and is polarized in theorientation that is selectively passed by the polarizing filter of thesub-region 805, 815, 825. Similarly, a distant component of thepolarization-multiplexed beam can include the image content to bedisplayed in the remainder of the EPE 800′, 810′, 820′, and is polarizedin the orientation that is selectively passed by the polarizing filterof the remainder of the EPE 800′, 810′, 820′. A polarization-multiplexedbeam as described herein can be generated, for example, by sending lightfrom a display 900, such as a fiber scanning display described herein,through a polarizer 905 and a polarization modulator 910 to createpolarization modulated beams 770, 780, 790. The polarization modulator910 may comprise, for example, a liquid crystal modulator comprising aliquid crystal layer disposed between electrodes configured to apply avoltage (e.g., from the control electronics) across the liquid crystallayer so as to cause linearly polarized light to rotate. The polarizer905 can polarize the light providing as an output, for example, linearlypolarized light. The polarization modulator can then rotate thepolarization (e.g., rotate the polarization angle of linearly polarizedlight) and thereby modulate the amount of rotation of the polarization.The polarization modulator 910 may thus modulate or change thepolarization from a first polarization state or the first polarizationcorresponding to the polarization that is passed by the firstpolarization filter 915 and blocked by the second polarization filter920 to a second polarization state or the second polarization that ispassed by the second polarization filter 920 and blocked by the firstpolarization filter 915. Beams 770, 780, 790 can then be sent into thewaveguide stack 660 at in-coupling elements 700, 710, 720 as describedherein. When the light is out-coupled at EPEs 800′, 810′, 820′ includingsub-regions 805, 815, 825 or the other portions of the EPE's, the lightpasses through either of the first polarizing filter 915 or the secondpolarizing filter 920 to selectively project one of the components ofthe polarization-multiplexed beam (e.g., the first or second portions ofthe image content corresponding to the far or near image content) to theeye of a viewer.

In another example, as depicted in FIG. 11B, a time divisionmultiplexing system comprising first and second shutters associated withfirst and second regions of the exit pupil expander that are configuredto present far image content through the first region while blocking thesecond region with the second shutter and present near image contentthrough the second region at a different time while blocking the firstregion with the first shutter. The time division multiplexing system mayinclude control electronics configured to drive/control the shutters andestablish the appropriate timing of the presentation of the differentimage content from the different regions. Separation of image contentbetween the near and distant regions may be achieved by providing liquidcrystal shutters 930, 925 on the sub-region 805, 815, 825 and theremainder of the EPE 800′, 810′, 820′. Similar to the polarizing filtersdescribed above, separately controllable liquid crystal shutters 930,925 may be provided for each of the regions of the EPE 800′, 810′, 820′.In the example configuration of FIG. 11B, liquid crystal shutter 930 iscoextensive with the sub-region 805, 815, 825, while liquid crystalshutter 925 is coextensive with the remainder of the EPE 800′, 810′,820′. The liquid crystal shutters 925, 930 may each comprise liquidcrystal layers disposed between electrodes arranged to apply a voltage(e.g., from the control electronics) across the liquid crystal layers.The liquid crystal shutters 925, 930 further may comprise a polarizerand an analyzer (another polarizer). Each liquid crystal film or layermay be controllable by applying a voltage (e.g., from the controlelectronics) across the film to change the polarization of the film, forexample, between two alternate perpendicular orientations. For example,light initially propagates through the polarizer to provide polarizedlight such as linearly polarized light. The liquid crystal film receivesthis linearly polarized light. The liquid crystal film may rotate thepolarization (e.g., the polarization angle of linearly polarized light)depending on the voltage applied to the liquid crystal film via theelectrodes. Accordingly, the linear polarization of the light may bemade to be parallel or perpendicular to the linear polarization statethat is transmitted by the analyzer. Thus, when distant image content isbeing displayed, the voltages across the two liquid crystal shutters maybe selected such that the out-coupled light in the sub-region 805, 815,825 is blocked while the out-coupled light in the remainder of the EPE800′, 810′, 820′ is passed. Similarly, when near image content is beingdisplayed, the voltages across the two liquid crystal shutters may beselected such that the out-coupled light in the sub-region 805, 815, 825is passed while the out-coupled light in the remainder of the EPE 800′,810′, 820′ is blocked.

The shutters need not completely block ambient light from the worldforward of the wearer and the head mounted display. For example, insteadof comprising two polarizers (a polarizer and an analyzer), the shuttersmay comprise an analyzer and no polarizer preceding the liquid crystalfilm. Accordingly, un-polarized ambient light from the objects in theenvironment or world forward of the wearer and the head mounted displaymay pass through the analyzer regardless of whether the liquid crystalfilm rotates linearly polarized light or not. In such a design, bycontrast, the light from the display may comprise linearly polarizedlight. For example, the head mounted display device may include apolarizer disposed in the optical path between the display and thein-coupling optical element of the waveguide, or the waveguide itselfmay include a polarizing element. The in-coupling element may, forexample, be polarization selective and thus comprise a polarizer. Such apolarizer or polarizing element may yield linearly polarized light thatmay be rotated by the liquid crystal film depending on the voltageapplied (e.g., from the control electronics) to the liquid crystal film.Accordingly, the liquid crystal film and the analyzer can operate as ashutter for the light from the display that may be selectively open andclosed to allow light from the display to pass or be blocked; however,ambient light from objects forward the wearer and the head mounteddisplay may pass through regardless of the state of the shutter. In thismanner, when the shutter is closed to light from the display, the usercan still see through the eyepiece to the world forward the viewer andthe head mounted display.

In a third example, separation of image content between the near anddistant regions of the EPE 800′, 810′, 820′ may be achieved byselectively projecting image content to the sub-regions 805, 815, 825and remainder of the EPE 800′, 810′, 820′ based on a wearer's gazedirection and/or head pose. As illustrated in FIG. 6, the head mounteddisplay device may include an eye tracking camera 630 and/or head poseorientation sensor. Such a head pose orientation sensor may comprise,for example, one or more accelerometers, gyros, motion sensors, GPScomponents, etc., configured to assist in determining head movement,orientation, and/or position. The head mounted display may also compriseone or more eye tracking cameras 630 and processing electronicsconfigured to determine the wearer's gaze direction. Thus the wearer'sgaze direction may be detected by an eye tracking camera 630 configuredto determine a gaze direction of the eye 210 and the gaze direction maybe used to determine what image content to present. (Alternativelyand/or additionally, head pose sensors may provide information regardingthe wearer's gaze.) For example, when the wearer's gaze is directed tothe sub-region 805, 815, 825, the electronics may cause the display toin-couple light including only the near image content and not thedistant image content. If the wearer is looking at the sub-region 805,815, 825, the wearer will see the near image content at the proper neardepth as provided by the sub-region 805, 815, 825. This near imagecontent may be at the lower portion of the frame or field or field ofview. The upper portion of the frame or field or field of view may notinclude image content. Similarly, when the wearer's gaze is directedtoward the remainder of the EPE 800′, 810′, 820′, the electronics maycause the display to in-couple light including only the distant imagecontent and not the near image content. If the wearer is looking at theremainder of the EPE 800′, 810′, 820′, the wearer will see the far imagecontent presented at the proper far depth as provided by the remainderof the EPE 800′, 810′, 820′. The far image content may be in the upperportion of the frame or field or field of view. The lower portion of theframe or field or field of view may not include image content.

In some embodiments, the system may be configured to project acombination of both near and distant image content. For example, awearer may be looking at distant image content, which is in the upperportion of the frame or field or field of view (or EPE 800′, 810′,820′), when the wearer receives image content more suitable for viewingat a near depth such as an email, text, etc. If the email is generallydisplayed as near image content, the display may notify the wearer bysimultaneously displaying both the existing distant image content andthe email content. The wearer may then see the email content, which willappear distant, for example, due to the optical power of the remainderof the EPE 800′, 810′, 820′, and may thereby be prompted to look down tothe sub-region 805, 815, 825. The eye tracking may detect this movementof the eye downward and may cause the display to present the emailcontent alone without the distant image content. The wearer gazing,downward, will see the e-mail through the sub-region 805, 815, 825 andthus the e-mail will appear to be nearer because of the optical powerassociated with the sub-region 805, 815, 825. The e-mail (or other imagecontent more suitable for viewing at a near depth plane) can thus beviewed in detail.

It is contemplated that the innovative aspects may be implemented in orassociated with a variety of applications and thus includes a wide rangeof variation. Variations, for example, in the shape, number, and/oroptical power of the EPE's are contemplated. The structures, devices andmethods described herein may particularly find use in displays such aswearable displays (e.g., head mounted displays) that can be used foraugmented and/or virtually reality. More generally, the describedembodiments may be implemented in any device, apparatus, or system thatcan be configured to display an image, whether in motion (such as video)or stationary (such as still images), and whether textual, graphical orpictorial. It is contemplated, however, that the described embodimentsmay be included in or associated with a variety of electronic devicessuch as, but not limited to: mobile telephones, multimedia Internetenabled cellular telephones, mobile television receivers, wirelessdevices, smartphones, Bluetooth® devices, personal data assistants(PDAs), wireless electronic mail receivers, hand-held or portablecomputers, netbooks, notebooks, smartbooks, tablets, printers, copiers,scanners, facsimile devices, global positioning system (GPS)receivers/navigators, cameras, digital media players (such as MP3players), camcorders, game consoles, wrist watches, clocks, calculators,television monitors, flat panel displays, electronic reading devices(e.g., e-readers), computer monitors, auto displays (including odometerand speedometer displays, etc.), cockpit controls and/or displays,camera view displays (such as the display of a rear view camera in avehicle), electronic photographs, electronic billboards or signs,projectors, architectural structures, microwaves, refrigerators, stereosystems, cassette recorders or players, DVD players, CD players, VCRs,radios, portable memory chips, washers, dryers, washer/dryers, parkingmeters, head mounted displays and a variety of imaging systems. Thus,the teachings are not intended to be limited to the embodiments depictedsolely in the Figures, but instead have wide applicability as will bereadily apparent to one having ordinary skill in the art.

Various modifications to the embodiments described in this disclosuremay be readily apparent to those skilled in the art, and the genericprinciples defined herein may be applied to other embodiments withoutdeparting from the spirit or scope of this disclosure. Thus, the claimsare not intended to be limited to the embodiments shown herein, but areto be accorded the widest scope consistent with this disclosure, theprinciples and the novel features disclosed herein. The word “exemplary”is used exclusively herein to mean “serving as an example, instance, orillustration.” Any embodiment described herein as “exemplary” is notnecessarily to be construed as preferred or advantageous over otherembodiments. Additionally, a person having ordinary skill in the artwill readily appreciate, the terms “upper” and “lower”, “above” and“below”, etc., are sometimes used for ease of describing the figures,and indicate relative positions corresponding to the orientation of thefigure on a properly oriented page, and may not reflect the properorientation of the structures described herein, as those structures areimplemented.

Certain features that are described in this specification in the contextof separate embodiments also can be implemented in combination in asingle embodiment. Conversely, various features that are described inthe context of a single embodiment also can be implemented in multipleembodiments separately or in any suitable subcombination. Moreover,although features may be described above as acting in certaincombinations and even initially claimed as such, one or more featuresfrom a claimed combination can in some cases be excised from thecombination, and the claimed combination may be directed to asubcombination or variation of a subcombination.

Similarly, while operations are depicted in the drawings in a particularorder, this should not be understood as requiring that such operationsbe performed in the particular order shown or in sequential order, orthat all illustrated operations be performed, to achieve desirableresults. Further, the drawings may schematically depict one more exampleprocesses in the form of a flow diagram. However, other operations thatare not depicted can be incorporated in the example processes that areschematically illustrated. For example, one or more additionaloperations can be performed before, after, simultaneously, or betweenany of the illustrated operations. In certain circumstances,multitasking and parallel processing may be advantageous. Moreover, theseparation of various system components in the embodiments describedabove should not be understood as requiring such separation in allembodiments, and it should be understood that the described programcomponents and systems can generally be integrated together in a singlesoftware product or packaged into multiple software products.Additionally, other embodiments are within the scope of the followingclaims. In some cases, the actions recited in the claims can beperformed in a different order and still achieve desirable results.

Various example embodiments of the invention are described herein.Reference is made to these examples in a non-limiting sense. They areprovided to illustrate more broadly applicable aspects of the invention.Various changes may be made to the invention described and equivalentsmay be substituted without departing from the true spirit and scope ofthe invention. In addition, many modifications may be made to adapt aparticular situation, material, composition of matter, process, processact(s) or step(s) to the objective(s), spirit or scope of the presentinvention. Further, as will be appreciated by those with skill in theart that each of the individual variations described and illustratedherein has discrete components and features which may be readilyseparated from or combined with the features of any of the other severalembodiments without departing from the scope or spirit of the presentinventions. All such modifications are intended to be within the scopeof claims associated with this disclosure.

The invention includes methods that may be performed using the subjectdevices. The methods may comprise the act of providing such a suitabledevice. Such provision may be performed by the end user. In other words,the “providing” act merely requires the end user obtain, access,approach, position, set-up, activate, power-up or otherwise act toprovide the requisite device in the subject method. Methods recitedherein may be carried out in any order of the recited events which islogically possible, as well as in the recited order of events.

Example aspects of the invention, together with details regardingmaterial selection and manufacture have been set forth above. As forother details of the present invention, these may be appreciated inconnection with the above-referenced patents and publications as well asgenerally known or appreciated by those with skill in the art. The samemay hold true with respect to method-based aspects of the invention interms of additional acts as commonly or logically employed.

In addition, though the invention has been described in reference toseveral examples optionally incorporating various features, theinvention is not to be limited to that which is described or indicatedas contemplated with respect to each variation of the invention. Variouschanges may be made to the invention described and equivalents (whetherrecited herein or not included for the sake of some brevity) may besubstituted without departing from the true spirit and scope of theinvention. In addition, where a range of values is provided, it isunderstood that every intervening value, between the upper and lowerlimit of that range and any other stated or intervening value in thatstated range, is encompassed within the invention.

Also, it is contemplated that any optional feature of the inventivevariations described may be set forth and claimed independently, or incombination with any one or more of the features described herein.Reference to a singular item, includes the possibility that there areplural of the same items present. More specifically, as used herein andin claims associated hereto, the singular forms “a,” “an,” “said,” and“the” include plural referents unless the specifically stated otherwise.In other words, use of the articles allow for “at least one” of thesubject item in the description above as well as claims associated withthis disclosure. It is further noted that such claims may be drafted toexclude any optional element. As such, this statement is intended toserve as antecedent basis for use of such exclusive terminology as“solely,” “only” and the like in connection with the recitation of claimelements, or use of a “negative” limitation.

Without the use of such exclusive terminology, the term “comprising” inclaims associated with this disclosure shall allow for the inclusion ofany additional element—irrespective of whether a given number ofelements are enumerated in such claims, or the addition of a featurecould be regarded as transforming the nature of an element set forth insuch claims. Except as specifically defined herein, all technical andscientific terms used herein are to be given as broad a commonlyunderstood meaning as possible while maintaining claim validity.

The breadth of the present invention is not to be limited to theexamples provided and/or the subject specification, but rather only bythe scope of claim language associated with this disclosure.

What is claimed is:
 1. An eyepiece for a head mounted displaycomprising: a waveguide stack comprising a first waveguide layer havinga front face, a rear face and a plurality of edges, said front face andsaid rear face having lateral dimensions, said edges having a thicknessless than the lateral dimensions of said front face and said rear facesuch that said first waveguide layer can guide light therein from alocation closer to one edge toward a location closer to another edge bytotal internal reflection from said front and rear faces; at least oneout-coupling optical element configured to receive light guided withinsaid first waveguide layer by total internal reflection from said frontface and said rear face and to out-couple light out of said front faceof said first waveguide layer; and at least one optical element havingoptical power such that said eyepiece outputs a first portion of saidlight guided within said first waveguide layer from a first region ofsaid eyepiece as if said light originated from a first depth withrespect to said waveguide stack and a second portion of light guidedwithin said first waveguide layer from a second region of said eyepieceas if said light originated from a second depth with respect to saidwaveguide stack, said second region being laterally displaced withrespect to said first region.
 2. The eyepiece of claim 1, wherein saidat least one optical element having optical power is included in ordisposed on said at least one out-coupling element.
 3. The eyepiece ofclaim 2, wherein said at least one out-coupling optical element includesa first region configured to out-couple light guided within said firstwaveguide layer as if said light originated from a first depth withrespect to said waveguide stack and a second region configured toout-couple light guided within said first waveguide layer as if saidlight originated from a second depth with respect to said waveguidestack, said first region of said at least one out-coupling opticalelement corresponding to said first region of said eyepiece and saidsecond region of said at least one out-coupling optical elementcorresponding to said second region of said eyepiece.
 4. The eyepiece ofclaim 1, wherein at least one of the at least one out-coupling opticalelement or the at least one element having optical power comprises adiffractive or holographic optical element.
 5. The eyepiece of claim 4,wherein the diffractive or holographic optical element comprises ananalog surface relief grating (ASR), a binary surface relief structure(BSR), or a switchable diffractive optical element.
 6. The eyepiece ofclaim 1, wherein the at least one optical element having optical powercomprises a refracting surface that has optical power.
 7. The eyepieceof claim 1, further comprising an in-coupling optical element configuredto in-couple light into the first waveguide layer.
 8. The eyepiece ofclaim 7, further comprising a light distributing element configured toreceive light from the in-coupling optical element and redirect saidlight toward said at least one out-coupling optical element.
 9. Theeyepiece of claim 1, wherein at least one of the first region and thesecond region of the eyepiece has a fixed optical power.
 10. Theeyepiece of claim 1, further comprising a multiplexing system configuredto selectively distribute a first portion of image content through thefirst region of the eyepiece and a second portion of the image contentthrough the second region of the eyepiece.
 11. The eyepiece of claim 10,wherein the eyepiece is included in a head mounted display to be worn onthe head of a wearer having a field of view that includes said eyepieceand objects forward said eyepiece, the first portion of the imagecontent comprising image content to be presented in the portion of thefield of view of the wearer coinciding with the first region of theeyepiece while the second portion of the image content comprises imagecontent to be presented in the portion of the field of view of thewearer coinciding with the second region of the eyepiece.
 12. Theeyepiece of claim 11, wherein the image content in the first portion ofthe image content is not visible to the wearer in the portion of thefield of view of the wearer coinciding with the second region of theeyepiece while the image content in the second portion of the imagecontent is not visible to the wearer in the portion of the field of viewof the wearer coinciding with the first region of the eyepiece.
 13. Theeyepiece of claim 10, wherein the first region of the eyepiece isforward and central of a wearer's eye while the second region of theeyepiece is below the first region, and the image content presentedthrough the first region of the eyepiece corresponds to far imagecontent while the image content presented through the second region ofthe eyepiece corresponds to near image content.
 14. The eyepiece ofclaim 10, wherein the multiplexing system comprises a polarizationmodulator and respective first and second polarization filtersassociated with respective first and second regions of the eyepiece. 15.The eyepiece of claim 14, wherein the polarization modulator comprises aliquid crystal modulator comprising a liquid crystal layer disposedbetween electrodes configured to apply a voltage across the liquidcrystal layer so as to cause linearly polarized light to rotatepolarization angle.
 16. The eyepiece of claim 10, wherein themultiplexing system is configured to present a first portion of theimage content corresponding to first far image content through the firstregion of the eyepiece while blocking the first portion of the imagecontent from exiting the second region of the eyepiece.
 17. The eyepieceof claim 10, where the multiplexing system is configured to present asecond portion of the image content corresponding to second near imagecontent through the second region of the eyepiece while blocking thesecond portion of the image content from exiting the first region of theeyepiece.
 18. The eyepiece of claim 10, wherein the multiplexer systemcomprises first and second shutters and the eyepiece is configured topresent far image content through the first region of the eyepiece whileblocking the second region of the eyepiece with the second shutter andpresent near image content through the second region of the eyepiece ata different time while blocking the first region of the eyepiece withthe first shutter.
 19. The eyepiece of claim 18, wherein the shutterseach comprise liquid crystal layers disposed between electrodes arrangedto apply a voltage across the liquid crystal layers.
 20. The eyepiece ofclaim 19, wherein the liquid crystal shutters further comprise apolarizer and an analyzer.
 21. The eyepiece of claim 20, wherein thepolarizer is configured to provide linearly polarized light that isreceived by the liquid crystal layer and the liquid crystal layer isconfigured to rotate the polarization angle of the linear polarizedlight depending on the voltage applied to the liquid crystal layer viathe electrodes such that said linear polarization of the light may bemade to be parallel or perpendicular to the linear polarization statethat is transmitted by the analyzer.
 22. The eyepiece of claim 18,wherein when distant image content is to be displayed, the two shuttersmay be set such that the distant image content is passed through thefirst region of the eyepiece while the distant image content from thesecond region of the eyepiece is blocked while when near image contentis being displayed, the two shutters may be set such that the near imagecontent is passed through the second region of the eyepiece while thenear image content from the first region of the eyepiece is blocked. 23.A head mounted display comprising: a frame configured to mount on awearer; an eyepiece comprising: a waveguide stack comprising a firstwaveguide layer having a front face, a rear face and a plurality ofedges, said front face and said rear face having lateral dimensions,said edges having a thickness less than the lateral dimensions of saidfront face and said rear face such that said first waveguide layer canguide light therein from a location closer to one edge toward a locationcloser to another edge by total internal reflection from said front andrear faces; at least one out-coupling optical element configured toreceive light guided within said first waveguide layer by total internalreflection from said front face and said rear face and to out-couplelight out of said front face of said first waveguide layer; and at leastone optical element having optical power such that said eyepiece outputsa first portion of said light guided within said first waveguide layerfrom a first region of said eyepiece as if said light originated from afirst depth with respect to said waveguide stack and a second portion oflight guided within said first waveguide layer from a second region ofsaid eyepiece as if said light originated from a second depth withrespect to said waveguide stack, said second region being laterallydisplaced with respect to said first region; and a display configured toselectively couple into the eyepiece light comprising near image contentand light comprising distant image content.
 24. The head mounted displayof claim 23, further comprising at least one eye tracking cameraconfigured to track a gaze of the wearer's eye.
 25. The head mounteddisplay of claim 24, wherein the eye tracking camera is configured suchthat when the wearer's gaze is directed to the first region of theeyepiece, the display may couple into the eye piece light comprisingnear image content and not distant image content, and when the wearer'sgaze is directed toward the second region of the eyepiece, the displaymay couple into the eyepiece light comprising distant image content andnot near image content.
 26. The head mounted display of claim 23,further comprising at least one head pose sensor configured to assist indetermining at least one of head movement, head orientation, and headposition.
 27. The head mounted display of claim 26, wherein the headpose sensor is configured such that the display selectively couples intothe eyepiece light comprising near image content and not distant imagecontent, or light comprising distant image content and not near imagecontent, based on at least one of the head movement, head orientation,and head position of the wearer.
 28. The head mounted display of claim23, wherein said head mounted display comprises an augmented realityhead mounted display.
 29. The head mounted display of claim 23, whereinsaid head mounted display comprises a virtual reality head mounteddisplay.